Renu Malhotra
- Professor, Planetary Sciences
- Regents Professor, Planetary Sciences
- Regents Professor, Lunar and Planetary Laboratory
- Professor, Applied Mathematics - GIDP
- Professor, Louise Foucar Marshall Science Research
- Member of the Graduate Faculty
- Professor, Aerospace-Mechanical Engineering
- (520) 626-5899
- Gerard P. Kuiper Space Sci., Rm. 00515
- Tucson, AZ 85721
- renu@lpl.arizona.edu
Biography
Renu Malhotra is Louise Foucar Marshall Science Research Professor and Regents' Professor of Planetary Sciences at The University of Arizona in Tucson, where she is also serving as Chair of the Theoretical Astrophysics Program. She was born in New Delhi and grew up in Hyderabad, India. She earned her M.S. in Physics from the Indian Institute of Technology in Delhi in 1983, and her Ph.D. in Physics from Cornell University in 1988. She did post-doctoral research at Cornell and at Caltech, and worked as a staff scientist at the Lunar and Planetary Institute in Houston. Her work in planetary dynamics has spanned a wide variety of topics, including extra-solar planets and debris disks around nearby stars, the formation and evolution of the Kuiper belt and the asteroid belt, the orbital resonances amongst the moons of the giant planets, and the meteoritic bombardment history of the planets. She has revolutionized our understanding of the history of the solar system by using the orbital resonance between Pluto and Neptune to infer large-scale orbital migration of the giant planets and to predict the existence of the "Plutinos" and other small planets in resonance with Neptune. She is an elected member of the National Academy of Sciences and of the American Academy of Arts and Sciences, and has been the recipient of honors and awards from the American Astronomical Society, the International Astronomical Union, The University of Arizona, and the IIT-Delhi.
Awards
- Regents' Professor
- Board of Regents, The University of Arizona, Spring 2017
- Louise Foucar Marshall Science Research Professor
- College of Science, The University of Arizona, Spring 2016
- Fellow of American Academy of Arts and Sciences
- American Academy of Arts and Sciences, Spring 2015
- Member of National Academy of Sciences
- National Academy of Sciences, Spring 2015
- Galileo Circle Fellow
- University of Arizona - College of Science, Spring 2010
- Distinguished Alumna
- Indian Institute of Technology, Delhi, India, Spring 2006
Interests
Teaching
Celestial Mechanics, Planetary Science
Research
Planetary Dynamics, Theoretical Astrophysics
Courses
2024-25 Courses
-
Alien Earths
ASTR 170A1 (Spring 2025) -
Alien Earths
PTYS 170A1 (Spring 2025) -
Dissertation
AME 920 (Fall 2024) -
Dissertation
PHYS 920 (Fall 2024)
2023-24 Courses
-
Dissertation
AME 920 (Spring 2024) -
Dissertation
PHYS 920 (Spring 2024) -
Solar System Dynamics
ASTR 553 (Spring 2024) -
Solar System Dynamics
PTYS 553 (Spring 2024) -
Independent Study
PHYS 599 (Fall 2023) -
Research
PTYS 900 (Fall 2023)
2022-23 Courses
-
Independent Study
PHYS 599 (Spring 2023) -
Research
PTYS 900 (Spring 2023) -
Independent Study
PHYS 599 (Fall 2022) -
Research
PTYS 900 (Fall 2022)
2021-22 Courses
-
Independent Study
PHYS 599 (Spring 2022) -
Research
PTYS 900 (Spring 2022) -
Solar System Dynamics
PTYS 553 (Spring 2022) -
Honors Thesis
ASTR 498H (Fall 2021) -
Independent Study
PHYS 599 (Fall 2021) -
Research
PTYS 900 (Fall 2021)
2020-21 Courses
-
Honors Thesis
ASTR 498H (Spring 2021) -
Independent Study
PHYS 599 (Spring 2021) -
Spec Tops in Planetary Science
PTYS 595B (Spring 2021) -
Research
PTYS 900 (Fall 2020)
2019-20 Courses
-
Solar System Dynamics
ASTR 553 (Spring 2020) -
Solar System Dynamics
PTYS 553 (Spring 2020)
2018-19 Courses
-
Univ+Hum:Origin+Destiny
ASTR 170B2 (Spring 2019) -
Univ+Hum:Origin+Destiny
PTYS 170B2 (Spring 2019) -
Astr,Comet,Kuipr Blt Obj
PTYS 416 (Fall 2018) -
Astr,Comet,Kuipr Blt Obj
PTYS 516 (Fall 2018)
2017-18 Courses
-
Research
PTYS 900 (Spring 2018) -
Solar System Dynamics
ASTR 553 (Spring 2018) -
Solar System Dynamics
PTYS 553 (Spring 2018) -
Research
PTYS 900 (Fall 2017)
2016-17 Courses
-
Univ+Hum:Origin+Destiny
ASTR 170B2 (Spring 2017) -
Univ+Hum:Origin+Destiny
PTYS 170B2 (Spring 2017) -
Astr,Comet,Kuipr Blt Obj
PTYS 416 (Fall 2016) -
Astr,Comet,Kuipr Blt Obj
PTYS 516 (Fall 2016)
2015-16 Courses
-
Solar System Dynamics
ASTR 553 (Spring 2016) -
Solar System Dynamics
PTYS 553 (Spring 2016)
Scholarly Contributions
Journals/Publications
- Castro-Cisneros, J. D., Malhotra, R., & Rosengren, A. J. (2023). Lunar ejecta origin of near-Earth asteroid Kamo'oalewa is compatible with rare orbital pathways. Communications Earth and Environment, 4(1), 372.
- Malhotra, R., & Chen, Z. (2023). Non-perturbative investigation of low-eccentricity exterior mean motion resonances. \mnras, 521(1), 1253-1263.
- Malhotra, R., & Roy, S. (2023). Modeling the Free Inclinations of the Classical Kuiper Belt with the von Mises-Fisher Distribution. Research Notes of the American Astronomical Society, 7(7), 143.
- Markwardt, L., Holler, B. J., Lin, H. W., Gerdes, D. W., Adams, F. C., Malhotra, R., & Napier, K. J. (2023). First Near-IR Spectroscopic Survey of Neptune Trojans with JWST: Distinct Surface Compositions of Red vs Ultra-Red Neptune Trojans. arXiv e-prints, arXiv:2310.03998.
- Matheson, I. C., Malhotra, R., & Keane, J. T. (2023). A von Mises-Fisher distribution for the orbital poles of the plutinos. \mnras, 522(3), 3298-3307.
- Matheson, I., & Malhotra, R. (2023). A Measurement of the Kuiper Belt's Mean Plane From Objects Classified By Machine Learning. \aj, 165(6), 241.
- Matheson, I., & Malhotra, R. (2023). VizieR Online Data Catalog: Machine learning classified Kuiper Belt Objects (Matheson+, 2023). VizieR Online Data Catalog, J/AJ/165/241.
- Schwamb, M. E., Jones, R. L., Yoachim, P., Volk, K., Dorsey, R. C., Opitom, C., Greenstreet, S., Lister, T., Snodgrass, C., Bolin, B. T., Inno, L., Bannister, M. T., Eggl, S., Solontoi, M., Kelley, M. S., Juri{\'c}, M., Lin, H. W., Ragozzine, D., Bernardinelli, P. H., , Chesley, S. R., et al. (2023). Tuning the Legacy Survey of Space and Time (LSST) Observing Strategy for Solar System Science. \apjs, 266(2), 22.
- Dietrich, J., Apai, D., & Malhotra, R. (2022). An Integrative Analysis of the HD 219134 Planetary System and the Inner solar system: Extending DYNAMITE with Enhanced Orbital Dynamical Stability Criteria. \aj, 163(2), 88.
- Malhotra, R., & Ito, T. (2022). Pluto near the edge of chaos. Proceedings of the National Academy of Science, 119(15), 2118692119.
- Volk, K., & Malhotra, R. (2022). Orbital Dynamics Landscape near the Most Distant Known Trans-Neptunian Objects. \apj, 937(2), 119.
- Agol, E., Dorn, C., Grimm, S. L., Turbet, M., Ducrot, E., Delrez, L., Gillon, M., Demory, B., Burdanov, A., Barkaoui, K., Benkhaldoun, Z., Bolmont, E., Burgasser, A., Carey, S., Wit, J., Fabrycky, D., Foreman-Mackey, D., Haldemann, J., Hernandez, D. M., , Ingalls, J., et al. (2021). Refining the Transit-timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides. \psj, 2(1), 1.
- Dietrich, J., Apai, D., & Malhotra, R. (2021). An Integrative Analysis of the HD 219134 Planetary System and the Inner Solar System: Extending DYNAMITE with Enhanced Orbital Dynamical Stability Criteria. arXiv e-prints, arXiv:2112.05337.
- Hendler, N., Pascucci, I., Pinilla, P., Tazzari, M., Carpenter, J., Malhotra, R., & Testi, L. (2021). VizieR Online Data Catalog: ALMA observation of 152 1-11Myr aged stars (Hendler+, 2020). VizieR Online Data Catalog, J/ApJ/895/126.
- Malhotra, R. (2021). New results on orbital resonances. arXiv e-prints, arXiv:2111.09289.
- Reiland, N., Rosengren, A. J., Malhotra, R., & Bombardelli, C. (2021). Assessing and minimizing collisions in satellite mega-constellations. Advances in Space Research, 67(11), 3755-3774.
- Sharkey, B. N., Reddy, V., Malhotra, R., Thirouin, A., Kuhn, O., Conrad, A., Rothberg, B., Sanchez, J. A., Thompson, D., & Veillet, C. (2021). Lunar-like silicate material forms the Earth quasi-satellite (469219) 2016 HO$_3$ Kamoʻoalewa. Communications Earth and Environment, 2(1), 231.
- Zaveri, N., & Malhotra, R. (2021). Pluto's Resonant Orbit Visualized in 4D. Research Notes of the American Astronomical Society, 5(10), 235.
- Amato, D., Malhotra, R., Sidorenko, V., & Rosengren, A. J. (2020). Lunar close encounters compete with the circumterrestrial Lidov-Kozai effect. Celestial Mechanics and Dynamical Astronomy, 132(6-7), 35.
- Collaboration, V., Jones, R. L., Bannister, M. T., Bolin, B. T., Chandler, C. O., Chesley, S. R., Eggl, S., Greenstreet, S., Holt, T. R., Hsieh, H. H., Ivezi{\'c}, Z., Juri{\'c}, M., Kelley, M. S., Knight, M. M., Malhotra, R., Oldroyd, W. J., Sarid, G., Schwamb, M. E., Snodgrass, C., , Solontoi, M., et al. (2020). The Scientific Impact of the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) for Solar System Science. arXiv e-prints, arXiv:2009.07653.
- Hendler, N. P., & Malhotra, R. (2020). Observational Completion Limit of Minor Planets from the Asteroid Belt to Jupiter Trojans. The Planetary Science Journal, 1(3), 75.
- Hendler, N., Pascucci, I., Pinilla, P., Tazzari, M., Carpenter, J., Malhotra, R., & Testi, L. (2020). The Evolution of Dust Disk Sizes from a Homogeneous Analysis of 1-10 Myr old Stars. \apj, 895(2), 126.
- Malhotra, R., & Ingersoll, A. P. (2020). Adam P. Showman (1968-2020). \icarus, 345, 113780.
- Malhotra, R., & Zhang, N. (2020). On the divergence of first-order resonance widths at low eccentricities. \mnras, 496(3), 3152-3160.
- Markwardt, L., Gerdes, D., Malhotra, R., Becker, J., Hamilton, S., & Adams, F. (2020). Search for L5 Earth Trojans with DECam. \mnras, 492(4), 6105-6119.
- Petrovich, C., Mu{\~noz}, D. J., Kratter, K. M., & Malhotra, R. (2020). A Disk-driven Resonance as the Origin of High Inclinations of Close-in Planets. \apjl, 902(1), L5.
- Reiland, N., Rosengren, A. J., Malhotra, R., & Bombardelli, C. (2020). Assessing and Minimizing Collisions in Satellite Mega-Constellations. arXiv e-prints, arXiv:2002.00430.
- Volk, K., & Malhotra, R. (2020). Dynamical Instabilities in Systems of Multiple Short-period Planets Are Likely Driven by Secular Chaos: A Case Study of Kepler-102. \aj, 160(3), 98.
- Apai, D., Banzatti, A., Ballering, N. P., Bergin, E. A., Bixel, A., Birnstiel, T., Bose, M., Brittain, S., Cadillo-Quiroz, H., Carrera, D., Ciesla, F., Close, L., Desch, S. J., Dong, C., Dressing, C. D., Fernandes, R. B., France, K., Gharib-Nezhad, E., Haghighipour, N., , Hartnett, H. E., et al. (2019). Planetary Habitability Informed by Planet Formation and Exoplanet Demographics. \baas, 51(3), 475.
- Lan, L., & Malhotra, R. (2019). Neptune's resonances in the scattered disk. Celestial Mechanics and Dynamical Astronomy, 131(8), 39.
- Malhotra, R. (2019). Resonant Kuiper belt objects: a review. Geoscience Letters, 6(1), 12.
- Malhotra, R. (2019). The case for a deep search for Earth's Trojan asteroids. Nature Astronomy, 3, 193-194.
- Rizk, B., Drouet, d. C., Hergenrother, C., Bos, B., Golish, D., Malhotra, R., Lauretta, D., Butt, J., Patel, J., Fitzgibbon, M., May, C., Bierhaus, E., Freund, S., Fisher, M., Cambioni, S., Bennett, C., Balram-Knutson, S., Harshman, K., DellaGiustina, D., , Antreasian, P., et al. (2019). OSIRIS-REx low-velocity particles during outbound cruise. Advances in Space Research, 63(1), 672-691.
- Su, K. Y., Jackson, A. P., G{\'asp\'ar}, A., Rieke, G. H., Dong, R., Olofsson, J., Kennedy, G., Leinhardt, Z. M., Malhotra, R., Hammer, M., Meng, H. Y., Rujopakarn, W., Rodriguez, J. E., Pepper, J., Reichart, D., James, D., & Stassun, K. G. (2019). Extreme Debris Disk Variability: Exploring the Diverse Outcomes of Large Asteroid Impacts During the Era of Terrestrial Planet Formation. \aj, 157(5), 202.
- Su, K., Jackson, A., Gaspar, A., Rieke, G., Dong, R., Olofsson, J., Kennedy, G., Leinhardt, Z., Malhotra, R., Hammer, M., Meng, H., Rujopakarn, W., Rodriguez, J., Pepper, J., Reichart, D., James, D., & Stassun, K. (2019). VizieR Online Data Catalog: IRAC fluxes of the ID8 and P1121 systems (Su+, 2019). VizieR Online Data Catalog, J/AJ/157/202.
- Volk, K., & Malhotra, R. (2019). Not a Simple Relationship between Neptune\textquoterights Migration Speed and Kuiper Belt Inclination Excitation. \aj, 158(2), 64.
- Walsh}, K., Jawin, E., Ballouz, R. -., Barnouin, O., Bierhaus, E., Connolly, H., Molaro, J., McCoy, T., Delbo', M., Hartzell, C., Pajola, M., Schwartz, S., Trang, D., Asphaug, E., Becker, K., Beddingfield, C., Bennett, C., Bottke, W., Burke, K., , Clark, B., et al. (2019). Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface. Nature Geoscience, 12(4), 242-246.
- Walsh}, K., Jawin, E., Ballouz, R. -., Barnouin, O., Bierhaus, E., Connolly, H., Molaro, J., McCoy, T., Delbo', M., Hartzell, C., Pajola, M., Schwartz, S., Trang, D., Asphaug, E., Becker, K., Beddingfield, C., Bennett, C., Bottke, W., Burke, K., , Clark, B., et al. (2019). Publisher Correction: Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface. Nature Geoscience, 12(5), 399-399.
- Cambioni, S., & Malhotra, R. (2018). The Mid-plane of the Main Asteroid Belt. \aj, 155, 143.
- Malhotra, R., Lan, L., Volk, K., & Wang, X. (2018). Neptune's 5:2 Resonance in the Kuiper Belt. \aj, 156, 55.
- Strom, R., Marchi, S., & Malhotra, R. (2018). "Ceres and the terrestrial planets impact cratering record". icarus, 302, 104-108.
- Trilling, D., Bellm, E., & Malhotra, R. (2018). On the Detectability of Planet X with LSST. \aj, 155, 243.
- JeongAhn, Y., & Malhotra, R. (2017). "Simplified Derivation of the Collision Probability of Two Objects in Independent Keplerian Orbits". aj, 153, 235.
- Malhotra, R. (2017). "Prospects for unseen planets beyond Neptune". ArXiv e-prints.
- Malhotra, R., & Wang, X. (2017). "Eccentricity distribution in the main asteroid belt". mnras, 465, 4381-4389.
- Su, K., MacGregor, M., Booth, M., Wilner, D., Flaherty, K., Hughes, A., Phillips, N., Malhotra, R., Hales, A., Morrison, S., Ertel, S., Matthews, B., Dent, W., & Casassus, S. (2017). "ALMA 1.3 mm Map of the HD 95086 System". aj, 154, 225.
- Volk, K., & Malhotra, R. (2017). "The Curiously Warped Mean Plane of the Kuiper Belt". aj, 154, 62.
- Wang, X., & Malhotra, R. (2017). "Mean Motion Resonances at High Eccentricities: The 2:1 and the 3:2 Interior Resonances". aj, 154, 20.
- Malhotra, R., Volk, K., & Wang, X. (2016). CORRALLING A DISTANT PLANET WITH EXTREME RESONANT KUIPER BELT OBJECTS. ASTROPHYSICAL JOURNAL LETTERS, 824(2).
- {Yoshida}, F., {Ito}, T., {Dermawan}, B., {Nakamura}, T., {Takahashi}, S., {Ibrahimov}, M., {Malhotra}, R., {Ip}, W., {Chen}, W., {Sawabe}, Y., {Haji}, M., {Saito}, R., , M. (2016). Lightcurves of the Karin family asteroids. icarus, 269, 15-22.
- Malhotra, R. (2015). The Mass Distribution Function of Planets. apj, 808, 71.
- Morrison, S., & Malhotra, R. (2015). Planetary Chaotic Zone Clearing: Destinations and Timescales. apj, 799, 41.
- Strom, R. G., Renu, M., Xiao, Z., Ito, T., Yoshida, F., & Ostrach, L. R. (2015). The inner solar system cratering record and the evolution of impactor populations. Research in Astronomy and Astrophysics, 15, 407.
- Su, K. Y., Morrison, S., Malhotra, R., Smith, P. S., Balog, Z., & Rieke, G. H. (2015). Debris Distribution in HD 95086 - A Young Analog of HR 8799. apj, 799, 146.
- {JeongAhn}, Y., , R. (2015). "{The current impact flux on Mars and its seasonal variation}". icarus, 262, 140-153.
- {Kne{v z}evic}, Z., {Morbidelli}, A., {Burns}, J., {Athanssoula}, E., {Laskar}, J., {Malhotra}, R., {Mikkola}, S., {Peale}, S., , F. (2015). "{Division I: Commission 7: Celestial Mechanics {amp} Dynamical Astronomy}". Transactions of the International Astronomical Union, Series B, 28, 83-86.
- JeongAhn, Y., & Malhotra, R. (2014). On the non-uniform distribution of the angular elements of near-Earth objects. Icarus, 229, 236-246.More infoAbstract: We examine the angular distributions of near-Earth objects (NEOs) which are often regarded as uniform. The apparent distribution of the longitude of ascending node, Ω, is strongly affected by well-known seasonal effects in the discovery rate of NEOs. The deviation from the expected π-periodicity in the apparent distribution of Ω indicates that its intrinsic distribution is slightly enhanced along a mean direction, Ω[U+203E]=111°; approximately 53 % of NEOs have Ω values within ±90° of Ω[U+203E]. We also find that each subgroup of NEOs (Amors, Apollos and Atens) has different observational selection effects which cause different non-uniformities in the apparent distributions of their arguments of perihelion ψ, and longitudes of perihelion π{variant}. For their intrinsic distributions, our analysis reveals that the Apollo asteroids have non-uniform ψ due to secular dynamics associated with inclination-eccentricity-ψ coupling, and the Amors' π{variant} distribution is peaked towards the secularly forced eccentricity vector. The Apollos' ψ distribution is axial, favoring values near 0° and 180°; the two quadrants centered at 0° and 180° account for 55 % of the Apollos' ψ values. The Amors' π{variant} distribution peaks near π{variant}[U+203E]=4°; 61% of Amors have π{variant} within ±90° of this peak. We show that these modest but statistically significant deviations from uniform random distributions of angular elements are owed to planetary perturbations, primarily Jupiter's. It is remarkable that this strongly chaotic population of minor planets reveals the presence of Jupiter in its angular distributions. © 2013 Elsevier Inc.
- Malhotra, R. (2014). Orbital resonances in planetary systems. CELESTIAL MECHANICS of the Encyclopedia of Life Support Systems, 6.119.55.More infoPublisher: UNESCO
- Rodigas, T. J., Malhotra, R., & Hinz, P. M. (2014). Predictions for Shepherding Planets in Scattered Light Images of Debris Disks. apj, 780, 65.
- Malhotra, R. (2013). NASA Solar System Exploration portal profile. Fall.More infohttp://solarsystem.nasa.gov/people
- Malhotra, R. (2013). Our wild wild solar system. National Geographic.More infoCover story
- Petrovich, C., Malhotra, R., & Tremaine, S. (2013). Planets near mean-motion resonances. Astrophysical Journal, 770(1).More infoAbstract: The multiple-planet systems discovered by the Kepler mission exhibit the following feature: planet pairs near first-order mean-motion resonances prefer orbits just outside the nominal resonance, while avoiding those just inside the resonance. We explore an extremely simple dynamical model for planet formation, in which planets grow in mass at a prescribed rate without orbital migration or dissipation. We develop an analytic version of this model for two-planet systems in two limiting cases: the planet mass grows quickly or slowly relative to the characteristic resonant libration time. In both cases, the distribution of systems in period ratio develops a characteristic asymmetric peak-trough structure around the resonance, qualitatively similar to that observed in the Kepler sample. We verify this result with numerical integrations of the three-body problem. We show that for the 3 : 2 resonance, where the observed peak-trough structure is strongest, our simple model is consistent with the observations for a range of mean planet masses 20-100 M ⊕. This predicted mass range is higher - by at least a factor of three - than the range expected from the few Kepler planets with measured masses, but part of this discrepancy could be due to oversimplifications in the dynamical model or uncertainties in the planetary mass-radius relation. © 2013. The American Astronomical Society. All rights reserved..
- Su, K., Rieke, G. H., Malhotra, R., Stapelfeldt, K. R., Hughes, A. M., Bonsor, A., Wilner, D. J., Balog, Z., Watson, D. M., Werner, M. W., & Misselt, K. A. (2013). Asteroid Belts in Debris Disk Twins: Vega and Fomalhaut. The Astrophysical Journal, 763(2), 118.
- Volk, K., & Malhotra, R. (2013). Do Centaurs preserve their source inclinations?. Icarus, 224(1), 66-73.More infoAbstract: The Centaurs are a population of small, planet-crossing objects in the outer Solar System. They are dynamically short-lived and represent the transition population between the Kuiper belt and the Jupiter family short-period comets. Dynamical models and observations of the physical properties of the Centaurs indicate that they may have multiple source populations in the trans-Neptunian region. It has been suggested that the inclination distribution of the Centaurs may be useful in distinguishing amongst these source regions. The Centaurs, however, undergo many close encounters with the giant planets during their orbital evolution; here we show that these encounters can substantially determine the inclination distribution of the Centaurs. Almost any plausible initial inclination distribution of a Kuiper belt source results in Centaurs having inclinations peaked near 10-20°. Our studies also find that the Kuiper belt is an extremely unlikely source of the retrograde Centaur that has been observed. © 2013 Elsevier Inc.
- Belbruno, E., Moro-Martín, A., Malhotra, R., & Savransky, D. (2012). Chaotic exchange of solid material between planetary systems: implications for lithopanspermia.. Astrobiology, 12(8), 754-774.More infoPMID: 22897115;PMCID: PMC3440031;Abstract: We examined a low-energy mechanism for the transfer of meteoroids between two planetary systems embedded in a star cluster using quasi-parabolic orbits of minimal energy. Using Monte Carlo simulations, we found that the exchange of meteoroids could have been significantly more efficient than previously estimated. Our study is relevant to astrobiology, as it addresses whether life on Earth could have been transferred to other planetary systems in the Solar System's birth cluster and whether life on Earth could have been transferred from beyond the Solar System. In the Solar System, the timescale over which solid material was delivered to the region from where it could be transferred via this mechanism likely extended to several hundred million years (as indicated by the 3.8-4.0 Ga epoch of the Late Heavy Bombardment). This timescale could have overlapped with the lifetime of the Solar birth cluster (∼100-500 Myr). Therefore, we conclude that lithopanspermia is an open possibility if life had an early start. Adopting parameters from the minimum mass solar nebula, considering a range of planetesimal size distributions derived from observations of asteroids and Kuiper Belt objects and theoretical coagulation models, and taking into account Oort Cloud formation models, we discerned that the expected number of bodies with mass>10 kg that could have been transferred between the Sun and its nearest cluster neighbor could be of the order of 10(14) to 3·10(16), with transfer timescales of tens of millions of years. We estimate that of the order of 3·10(8)·l (km) could potentially be life-bearing, where l is the depth of Earth's crust in kilometers that was ejected as the result of the early bombardment.
- Knezevic, Z., Morbidelli, A., Burns, J., Athanassoula, E., Laskar, J., Malhotra, R., Mikkola, S., Peale, S., & Roig, F. (2012). Commission 7: Celestial Mechanics and Dynamical Astronomy. Transactions IAU, 7(T28A), 15-20.
- Volk, K., & Malhotra, R. (2012). The effect of orbital evolution on the Haumea (2003 EL 61) collisional family. Icarus, 221(1), 106-115.More infoAbstract: The Haumea family is currently the only identified collisional family in the Kuiper belt. We numerically simulate the long-term dynamical evolution of the family to estimate a lower limit of the family's age and to assess how the population of the family and its dynamical clustering are preserved over Gyr timescales. We find that the family is not younger than 100Myr, and its age is at least 1Gyr with 95% confidence. We find that for initial velocity dispersions of 50-400ms -1, approximately 20-45% of the family members are lost to close encounters with Neptune after 3.5Gyr of orbital evolution. We apply these loss rates to two proposed models for the formation of the Haumea family, a graze-and-merge type collision between two similarly sized, differentiated KBOs or the collisional disruption of a satellite orbiting Haumea. For the graze-and-merge collision model, we calculate that >85% of the expected mass in surviving family members within 150ms -1 of the collision has been identified, but that one to two times the mass of the known family members remains to be identified at larger velocities. For the satellite-break-up model, we estimate that the currently identified family members account for ∼50% of the expected mass of the family. Taking observational incompleteness into account, the observed number of Haumea family members is consistent with either formation scenario at the 1σ level, however both models predict more objects at larger relative velocities (>150ms -1) than have been identified. © 2012 Elsevier Inc.
- Volk, K., & Malhotra, R. (2012). The effect of orbital evolution on the Haumea (2003 EL61) collisional family. ICARUS, 221(1), 106-115.
- Katz, B., Dong, S., & Malhotra, R. (2011). Long-term cycling of Kozai-Lidov Cycles: Extreme eccentricities and inclinations excited by a distant eccentric perturber. Physical Review Letters, 107(18).More infoPMID: 22107620;Abstract: The very long-term evolution of the hierarchical restricted three-body problem is calculated analytically for high inclinations. The Kozai-Lidov Cycles (KLCs) slowly evolve due to the octupole term in the perturber's potential and exhibit striking features, including extremely high eccentricities and the generation of retrograde orbits with respect to the perturber. These features were found in recent numerical experiments of the nonrestricted three-body problem and were attributed inaccurately to the comparable and low masses of the two orbiting companions. Our calculation is done by averaging for the first time the double averaged secular equations of motion over the KLCs and finding a new constant of the motion. These very long-term effects are likely to be important in various astrophysical systems thought to involve KLCs, such as hot Jupiters, irregular moons of planets, and many others. © 2011 American Physical Society.
- Malhotra, R., & Strom, R. G. (2011). Comment on "Constraints on the source of lunar cataclysm impactors" (Cuk et al., 2010, Icarus 207, 590-594). Icarus, 216(1), 359-362.More infoAbstract: Cuk et al. (Cuk, M., Gladman, B.J., Stewart, S.T. [2010]. Icarus 207, 590-594) argue that the projectiles bombarding the Moon at the time of the so-called lunar cataclysm could not have been mainbelt asteroids ejected by purely gravitational means, in contradiction with a conclusion that was reached by Strom et al. (Strom, R.G., Malhotra, R., Ito, T., Yoshida, F., Kring, D.A. [2005]. Science 309, 1847-1850). We demonstrate that Cuk et al.'s argument is erroneous because, contrary to their arguments, the lunar highlands do register the cataclysm impacts, lunar class 1 craters do not represent the size distribution of the cataclysm craters, and the crater size distributions on the late-forming basins are quite similar to those of the highlands craters, albeit at a lower number density due to the rapid decline of the impact flux during the cataclysm. © 2010 Elsevier Inc.
- Minton, D. A., & Malhotra, R. (2011). Secular resonance sweeping of the main asteroid belt during planet migration. Astrophysical Journal, 732(1).More infoAbstract: We calculate the eccentricity excitation of asteroids produced by the sweeping ν6 secular resonance during the epoch of planetesimal-driven giant planet migration in the early history of the solar system. We derive analytical expressions for the magnitude of the eccentricity change and its dependence on the sweep rate and on planetary parameters; the ν6 sweeping leads to either an increase or a decrease of eccentricity depending on an asteroid's initial orbit. Based on the slowest rate of ν6 sweeping that allows a remnant asteroid belt to survive, we derive a lower limit on Saturn's migration speed of ∼ 0.15 AU Myr -1 during the era that the ν6 resonance swept through the inner asteroid belt (semimajor axis range 2.1-2.8 AU). This rate limit is for Saturn's current eccentricity and scales with the square of its eccentricity; the limit on Saturn's migration rate could be lower if its eccentricity were lower during its migration. Applied to an ensemble of fictitious asteroids, our calculations show that a prior single-peaked distribution of asteroid eccentricities would be transformed into a double-peaked distribution due to the sweeping of the ν6 resonance. Examination of the orbital data of main belt asteroids reveals that the proper eccentricities of the known bright (H ≤ 10.8) asteroids may be consistent with a double-peaked distribution. If so, our theoretical analysis then yields two possible solutions for the migration rate of Saturn and for the dynamical states of the pre-migration asteroid belt: a dynamically cold state (single-peaked eccentricity distribution with mean of ∼ 0.05) linked with Saturn's migration speed 4 AU Myr-1 or a dynamically hot state (single-peaked eccentricity distribution with mean of ∼ 0.3) linked with Saturn's migration speed ∼ 0.8 AU Myr-1. © 2011. The American Astronomical Society. All rights reserved.
- Volk, K., & Malhotra, R. (2011). Inclination mixing in the classical Kuiper Belt. Astrophysical Journal, 736(1).More infoAbstract: We investigate the long-term evolution of the inclinations of the known classical and resonant Kuiper Belt objects (KBOs). This is partially motivated by the observed bimodal inclination distribution and by the putative physical differences between the low- and high-inclination populations. We find that some classical KBOs undergo large changes in inclination over gigayear timescales, which means that a current member of the low-inclination population may have been in the high-inclination population in the past, and vice versa. The dynamical mechanisms responsible for the time variability of inclinations are predominantly distant encounters with Neptune and chaotic diffusion near the boundaries of mean motion resonances. We reassess the correlations between inclination and physical properties including inclination time variability. We find that the size-inclination and color-inclination correlations are less statistically significant than previously reported (mostly due to the increased size of the data set since previous works with some contribution from inclination variability). The time variability of inclinations does not change the previous finding that binary classical KBOs have lower inclinations than non-binary objects. Our study of resonant objects in the classical Kuiper Belt region includes objects in the 3:2, 7:4, 2:1, and eight higher-order mean motion resonances. We find that these objects (some of which were previously classified as non-resonant) undergo larger changes in inclination compared to the non-resonant population, indicating that their current inclinations are not generally representative of their original inclinations. They are also less stable on gigayear timescales. © 2011. The American Astronomical Society. All rights reserved.
- Ito, T., & Malhotra, R. (2010). Asymmetric impacts of near-Earth asteroids on the Moon. Astronomy and Astrophysics, 519(7).More infoAbstract: Context. Recent lunar crater studies have revealed an asymmetric distribution of rayed craters on the lunar surface. The asymmetry is related to the synchronous rotation of the Moon: there is a higher density of rayed craters on the leading hemisphere compared with the trailing hemisphere. Rayed craters represent generally the youngest impacts. Aims. The purpose of this paper is to test the hypotheses that (i) the population of Near-Earth asteroids (NEAs) is the source of the impactors that have made the rayed craters; and (ii) that impacts by this projectile population account quantitatively for the observed asymmetry. Methods. We carried out numerical simulations of the orbital evolution of a large number of test particles representing NEAs in order to determine directly their impact flux on the Moon. The simulations were done in two stages. In the first stage we obtained encounter statistics of NEAs on the Earth's activity sphere. In the second stage we calculated the direct impact flux of the encountering particles on the surface of the Moon; the latter calculations were confined within the activity sphere of the Earth. A steady-state synthetic population of NEAs was generated from a debiased orbital distribution of the known NEAs. Results. We find that the near-Earth asteroids do have an asymmetry in their impact flux on the Moon: apex-to-antapex ratio of 1.32 ± 0.01. However, the observed rayed crater distribution's asymmetry is significantly more pronounced: apex-to-antapex ratio of 1.65 ± 0.16. Our results suggest the existence of an undetected population of slower (low impact velocity) projectiles, such as a population of objects nearly coorbiting with Earth; more observational studies of young lunar craters is needed to secure this conclusion. © 2010 ESO.
- Minton, D. A., & Malhotra, R. (2010). Dynamical erosion of the asteroid belt and implications for large impacts in the inner Solar System. Icarus, 207(2), 744-757.More infoAbstract: The cumulative effects of weak resonant and secular perturbations by the major planets produce chaotic behavior of asteroids on long timescales. Dynamical chaos is the dominant loss mechanism for asteroids with diameters D≳10km in the current asteroid belt. In a numerical analysis of the long-term evolution of test particles in the main asteroid belt region, we find that the dynamical loss history of test particles from this region is well described with a logarithmic decay law. In our simulations the loss rate function that is established at t≈1Myr persists with little deviation to at least t=4Gyr. Our study indicates that the asteroid belt region has experienced a significant amount of depletion due to this dynamical erosion-having lost as much as ∼50% of the large asteroids-since 1 Myr after the establishment of the current dynamical structure of the asteroid belt. Because the dynamical depletion of asteroids from the main belt is approximately logarithmic, an equal amount of depletion occurred in the time interval 10-200 Myr as in 0.2-4 Gyr, roughly ∼30% of the current number of large asteroids in the main belt over each interval. We find that asteroids escaping from the main belt due to dynamical chaos have an Earth-impact probability of ∼0.3%. Our model suggests that the rate of impacts from large asteroids has declined by a factor of 3 over the last 3 Gyr, and that the present-day impact flux of D>10km objects on the terrestrial planets is roughly an order of magnitude less than estimates currently in use in crater chronologies and impact hazard risk assessments. © 2009 Elsevier Inc.
- Bailey, B. L., & Malhotra, R. (2009). Two dynamical classes of Centaurs. Icarus, 203(1), 155-163.More infoAbstract: The Centaurs are a transient population of small bodies in the outer Solar System whose orbits are strongly chaotic. These objects typically suffer significant changes of orbital parameters on timescales of a few thousand years, and their orbital evolution exhibits two types of behaviors described qualitatively as random walk and resonance-sticking. We have analyzed the chaotic behavior of the known Centaurs. Our analysis has revealed that the two types of chaotic evolution are quantitatively distinguishable: (1) the random walk type behavior is well described by so-called generalized diffusion in which the rms deviation of the semimajor axis grows with time t as ∼tH, with Hurst exponent H in the range 0.22-0.95, however (2) orbital evolution dominated by intermittent resonance sticking, with sudden jumps from one mean motion resonance to another, has poorly defined H. We further find that these two types of behavior are correlated with Centaur dynamical lifetime: most Centaurs whose dynamical lifetime is less than ∼22 Myr exhibit generalized diffusion, whereas most Centaurs of longer dynamical lifetimes exhibit intermittent resonance sticking. We also find that Centaurs in the diffusing class are likely to evolve into Jupiter-family comets during their dynamical lifetimes, while those in the resonance-hopping class do not. © 2009 Elsevier Inc. All rights reserved.
- Minton, D. A., & Malhotra, R. (2009). A record of planet migration in the main asteroid belt. Nature, 457(7233), 1109-1111.More infoPMID: 19242470;Abstract: The main asteroid belt lies between the orbits of Mars and Jupiter, but the region is not uniformly filled with asteroids. There are gaps, known as the Kirkwood gaps, in distinct locations that are associated with orbital resonances with the giant planets; asteroids placed in these locations will follow chaotic orbits and be removed. Here we show that the observed distribution of main belt asteroids does not fill uniformly even those regions that are dynamically stable over the age of the Solar System. We find a pattern of excess depletion of asteroids, particularly just outward of the Kirkwood gaps associated with the 5:2, the 7:3 and the 2:1 Jovian resonances. These features are not accounted for by planetary perturbations in the current structure of the Solar System, but are consistent with dynamical ejection of asteroids by the sweeping of gravitational resonances during the migration of Jupiter and Saturn ∼4 Gyr ago. ©2009 Macmillan Publishers Limited. All rights reserved.
- Su, K., Rieke, G. H., Stapelfeldt, K. R., Malhotra, R., Bryden, G., Smith, P. S., Misselt, K. A., Moro-Martin, A., & Williams, J. P. (2009). THE DEBRIS DISK AROUND HR 8799. ASTROPHYSICAL JOURNAL, 705(1), 314-327.
- Malhotra, R., & Minton, D. A. (2008). Prospects for the habitability of OGLE-2006-BLG-109L. Astrophysical Journal, 683(1 PART 2), L67-L70.More infoAbstract: The extrasolar system OGLE-2006-BLG-109L is the first multiple-planet system to be discovered by gravitational microlensing (reported by Gaudi et al. in 2008); the two large planets that have been detected have mass ratios, semimajor axis ratios, and equilibrium temperatures that are similar to those of Jupiter and Saturn; the mass of the host star is only 0.5 M⊙, and the system is more compact than our own solar system. We find that in the habitable zone of the host star, the two detected planets resonantly excite large orbital eccentricities on a putative Earth-mass planet, driving such a planet out of the habitable zone. We show that an additional inner planet of ≥0.3 M⊙ at ≤0.1 AU would suppress the eccentricity perturbation and greatly improve the prospects for habitability of the system. Thus, the planetary architecture of a potentially habitable OGLE-2006-BLG-109L planetary system-with two "terrestrial" planets and two Jovian planets-could bear very close resemblance to our own solar system. © 2008. The American Astronomical Society. All rights reserved. Printed in U.S.A.
- Volk, K., & Malhotra, R. (2008). The scattered disk as the source of the jupiter family comets. Astrophysical Journal, 687(1), 714-725.More infoAbstract: The short-period Jupiter family comets (JFCs) are thought to originate in the Kuiper Belt; specifically, a dynamical subclass of the Kuiper Belt known as the "scattered disk" is argued to be the dominant source of JFCs. However, the best estimates from observational surveys indicate that this source may fall short by more than 2 orders of magnitude of the estimates obtained from theoretical models of the dynamical evolution of Kuiper Belt objects into JFCs. We reexamine the scattered disk as a source of the JFCs and make a rigorous estimate of the discrepancy.We find that the uncertainties in the dynamical models combined with a change in the size distribution function of the scattered disk at faint magnitudes (small sizes) beyond the current observational limit offer a possible but problematic resolution to the discrepancy. We discuss several other possibilities: that the present population of JFCs is a large fluctuation above their long-term average, that larger scattered disk objects tidally break up into multiple fragments during close planetary encounters as their orbits evolve from the trans-Neptune zone to near Jupiter, or that there are alternative source populations that contribute significantly to the JFCs. Well-characterized observational investigations of the Centaurs, objects that are transitioning between the trans-Neptune Kuiper Belt region and the inner solar system, can test the predictions of the non-steady state and the tidal breakup hypotheses. The classical and resonant classes of the Kuiper Belt are worth reconsideration as significant additional or alternate sources of the JFCs. © 2008. The American Astronomical Society. All rights reserved.
- Minton, D. A., & Malhotra, R. (2007). Assessing the massive young SUN hypothesis to solve the warm young earth puzzle. Astrophysical Journal, 660(2 I), 1700-1706.More infoAbstract: A moderately massive young Sun has been proposed to resolve the so-called faint young Sun paradox. We calculate the time evolution of the solar mass that would be required by this hypothesis using a simple parameterized energy-balance model for Earth's climate. Our calculations show that the solar mass-loss rate would need to have been 2-3 orders of magnitude higher than at present for a time on the order of ∼2 Gyr. Such a mass-loss history is significantly at variance (both in the timescale and in the magnitude of the mass-loss rates) with that inferred from astronomical observations of mass loss in younger solar analogs. While suggestive, the astronomical data cannot completely rule out the possibility that the Sun had the required mass-loss history; therefore, we also examine the effects of the hypothetical historical solar mass loss on orbital dynamics in the solar system, with a view to identifying additional tests of the hypothesis. We find that ratios of planetary orbital spacings remain unchanged, relative locations of planetary mean motion and secular resonances remain unchanged, but resonance widths and the sizes of the Hill spheres of all planets increase as the Sun loses mass. The populations and dynamics of objects near resonances with the planets, as well as those of distant irregular satellites of the giant planets, may contain the signature of a more massive young Sun. Planetary and satellite orbits provide a few tests, but these are weak or non-unique. © 2007. The American Astronomical Society. All rights reserved.
- Moro-Martín, A., Carpenter, J. M., Meyer, M. R., Hillenbrand, L. A., Malhotra, R., Hollenbach, D., Najita, J., Henning, T., Kim, J. S., Bouwman, J., Silverstone, M. D., Hines, D. C., Wolf, S., Pascucci, I., Mamajek, E. E., & Lunine, J. (2007). Are debris disks and massive planets correlated?. Astrophysical Journal, 658(2 I), 1312-1321.More infoAbstract: Using data from the Spitzer Space Telescope Legacy Science Program Formation and Evolution of Planetary Systems (FEPS), we have searched for debris disks around nine FGK stars (2-10 Gyr), known from radial velocity (RV) studies to have one or more massive planets. Only one of the sources, HD 38529, has excess emission above the stellar photosphere; at 70 μm the signal-to-noise ratio in the excess is 4.7, while at λ< 30 μm there is no evidence of excess. The remaining sources show no excesses at any Spitzer wavelengths. Applying survival tests to the FEPS sample and the results for the FGK survey recently published in Bryden et al., we do not find a significant correlation between the frequency and properties of debris disks and the presence of close-in planets. We discuss possible reasons for the lack of a correlation. © 2007. The American Astronomical Society. All rights reserved.
- Moro-Martín, A., Malhotra, R., & Wolf, S. (2007). Signatures of planets in debris disks. ESA - Workshop on Dust in Planetary Systems, 113-122.More infoAbstract: Main sequence stars are commonly surrounded by debris disks, formed by cold far-IR-emitting dust that is thought to be continuously replenished by a reservoir of undetected dust-producing planetesimals. In a planetary system with a belt of planetesimals (like the Solar System's Kuiper Belt) and one or more interior giant planets, as the particles spiral inward due to Poynting-Robertson (P-R) drag they can get trapped in the mean motion resonances (MMRs) with the planets. This process can create structure in the dust disk, as the particles accumulate at certain semimajor axes. Sufficiently massive planets may also scatter and eject dust particles out of a planetary system, creating a dust depleted region inside the orbit of the planet, a feature that is common in most of the spatially debris disks observed so far. We have studied the efficiency of particle ejection and the resulting dust density contrast inside and outside the orbit of the planet, as a function of the planet's mass and orbital elements and the particle size. Because the debris disk structure is sensitive to long period planets, complementing a parameter space not covered by radial velocity and transit surveys, its study can help us learn about the diversity of planetary systems. Presently, the Spitzer Space Telescope is carrying out observations of debris disks most of which are spatially unresolved. It is interesting therefore to study how the structure carved by planets affects the shape of the disk's Spectral Energy Distribution (SED), and consequently if the SED can be used to infer the presence of planets. We have numerically calculated the 3-D equilibrium spatial density distributions of dust disks originated by a belt of planetesimals similar to the Kuiper Belt (KB) in the presence of interior giant planets in different planetary configurations (with planet masses ranging from 1-10 MJup in circular orbits with semimajor axis between 1 -30 AU). For each of these systems we calculate its SED for a representative sample of chemical compositions. We discuss what types of planetary systems can be distinguishable from one another and the main parameter degeneracies in the model SEDs. We find that the SEDs are degenerated, and therefore to unambiguously constrain the planet location we need to obtain high resolution images able to spatially resolve the disk. In the future, observatories like ALMA, LET, SAFIR, TPF and JWST will be able to image the dust in planetary systems analogous to our own.
- Moro-Martín, A., Malhotra, R., Carpenter, J. M., Hillenbrand, L. A., Wolf, S., Meyer, M. R., Hollenbach, D., Najita, J., & Henning, T. (2007). The dust, planetesimals, and planets of HD 38529. Astrophysical Journal, 668(2), 1165-1173.More infoAbstract: HD 38529 is a post-main-sequence G8 III/IV star (3.5 Gyr old) with a planetary system consisting of at least two planets having M sin i of 0.8 and 12.2 AJup, semimajor axes of 0.13 and 3.74 AU, and eccentricities of 0.25 and 0.35, respectively. Spitzer observations show that HD 38529 has an excess emission above the stellar photosphere, with a signal-to-noise ratio (S/N) at 70 μm of 4.7, a small excess at 33 μm (S/N = 2.6), and no excess
- Bernstein, G. M., Trilling, D. E., Allen, R. L., Brown, M. E., Holman, M., & Malhotra, R. (2006). Erratum: The size distribution of trans-Neptunian bodies (The Astronomical Journal (2004) 128 (1364)). Astronomical Journal, 131(4), 2364-.
- Ito, T., & Malhotra, R. (2006). Dynamical transport of asteroid fragments from the ν6 resonance. Advances in Space Research, 38(4), 817-825.More infoAbstract: A large disruption in the main asteroid belt can cause a large flux, an "asteroid shower", on the terrestrial planets. We quantitatively examine the hypothesis that such an event was the cause of the lunar late heavy bombardment (LHB). We performed numerical integrations of about 20,000 test particles starting in the vicinity of the ν6 secular resonance in the main asteroid belt. The purpose of these integrations is to calculate, for each of the terrestrial planets, the collision probability of asteroids coming from an asteroid break-up event in the inner part of the main belt. Compared with previous studies, we simulate nearly two orders of magnitude larger number of particles, and we include the orbital effects of the eight planets, Mercury to Neptune. We also examined in detail the orbital evolution of asteroid fragments once they enter the Earth's activity sphere, including the effect of the Earth-Moon orbit. We obtained the collision probability, the distributions of impact velocities, impact positions, and impact angles of asteroid fragments on the Moon. The collision probability with the Moon (∼0.1%) suggests that a fairly large parent body, 1000-1500 km in diameter, is required if the LHB event is to be ascribed to a single asteroid disruption. An even larger parent body is required for less favorable initial conditions than we investigated here. We conclude that an asteroid disruption event is not a viable explanation for the LHB. © 2006 COSPAR.
- Meyer, M. R., Hillenbrand, L. A., Backman, D., Beckwith, S., Bouwman, J., Brooke, T., Carpenter, J., Cohen, M., Cortes, S., Crockett, N., Gorti, U., Henning, T., Hines, D., Hollenbach, D., Kim, J. S., Lunine, J., Malhotra, R., Mamajek, E., Metchev, S., , Moro-Martin, A., et al. (2006). The formation and evolution of planetary systems: Placing our solar system in context with Spitzer. Publications of the Astronomical Society of the Pacific, 118(850), 1690-1710.More infoAbstract: We provide an overview of the Spitzer Legacy Program, Formation and Evolution of Planetary Systems, that was proposed in 2000, begun in 2001, and executed aboard the Spitzer Space Telescope between 2003 and 2006. This program exploits the sensitivity of Spitzer to carry out mid-infrared spectrophotometric observations of solar-type stars. With a sample of ∼328 stars ranging in age from ∼3 Myr to ∼3 Gyr, we trace the evolution of circumstellar gas and dust from primordial planet-building stages in young circumstellar disks through to older collisionally generated debris disks. When completed, our program will help define the timescales over which terrestrial and gas giant planets are built, constrain the frequency of planetesimal collisions as a function of time, and establish the diversity of mature planetary architectures. In addition to the observational program, we have coordinated a concomitant theoretical effort aimed at understanding the dynamics of circumstellar dust with and without the effects of embedded planets, dust spectral energy distributions, and atomic and molecular gas line emission. Together with the observations, these efforts will provide an astronomical context for understanding whether our solar system - and its habitable planet - is a common or a rare circumstance. Additional information about the FEPS project can be found on the team Web site. © 2006. The Astronomical Society of the Pacific. All rights reserved.
- Pascucci, I., Gorti, U., Hollenbach, D., Najita, J., Meyer, M. R., Carpenter, J. M., Hillenbrand, L. A., Herczeg, G. J., Padgett, D. L., Mamajek, E. E., Silverstone, M. D., Schlingman, W. M., Kim, J. S., Stobie, E. B., Bouwman, J., Wolf, S., Rodmann, J., Hines, D. C., Lunine, J., & Malhotra, R. (2006). Formation and evolution of planetary systems: Upper limits to the gas mass in disks around sun-like stars. Astrophysical Journal Letters, 651(2 I), 1177-1193.More infoAbstract: We have carried out a sensitive search for gas emission lines at IR and millimeter wavelengths for a sample of 15 young Sun-like stars selected from our dust disk survey with Spitzer. We have used mid-IR lines to trace the warm (300-100 K) gas in the inner disk and millimeter transitions of 12CO to probe the cold (∼20 K) outer disk. We report no gas line detections from our sample. Line flux upper limits are first converted to warm and cold gas mass limits using simple approximations allowing a direct comparison with values from the literature. We also present results from more sophisticated models following Gorti & Hollenbach that confirm and extend our simple analysis. These models show that the [S I] 25.23 μm line can set constraining limits on the gas surface density at the disk inner radius and traces disk regions up to a few AU. We find that none of the 15 systems have more than 0.04 MJ of gas within a few AU from the disk inner radius for disk radii from 1 to ∼40 AU. These gas mass upper limits even in the eight systems younger than ∼30 Myr suggest that most of the gas is dispersed early. The gas mass upper limits in the 10-40 AU region, which is mainly traced by our CO data, are
- Hahn, J. M., & Malhotra, R. (2005). Neptune's migration into a stirred-up kuiper belt: A detailed comparison of simulations to observations. Astronomical Journal, 130(5), 2392-2414.More infoAbstract: We use N-body simulations to examine the consequences of Neptune's outward migration into the Kuiper Belt, with the simulated end states being compared rigorously and quantitatively to the observations. These simulations confirm the 2003 findings of Chiang and coworkers, who showed that Neptune's migration into a previously stirred-up Kuiper Belt can account for the Kuiper Belt objects (KBOs) known to librate at Neptune's 5:2 resonance. We also find that capture is possible at many other weak, high-order mean-motion resonances, such as 11:6, 13:7, 13:6, 9:4, 7:3, 12:5, 8:3, 3:1, 7:2, and 4:1. The more distant of these resonances, such as the 9:4, 7:3, 5:2, and 3:1, can also capture particles in stable, eccentric orbits beyond 50 AU, in the region of phase space conventionally known as the "Scattered Disk." Indeed, 90% of the simulated particles that persist over the age of the solar system in the Scattered-Disk zone never had a close encounter with Neptune but instead were promoted into these eccentric orbits by Neptune's resonances during the migration epoch. This indicates that the observed Scattered Disk might not be so scattered. This model also produced only a handful of Centaurs, all of which originated at Neptune's mean-motion resonances in the Kuiper Belt. However, a noteworthy deficiency of the migration model considered here is that it does not account for the observed abundance of Main Belt KBOs having inclinations higher than 15°. In order to rigorously compare the model end state with the observed Kuiper Belt in a manner that accounts for telescopic selection effects, Monte Carlo methods are used to assign sizes and magnitudes to the simulated particles that survive over the age of the solar system. If the model considered here is indeed representative of the outer solar system's early history, then the following conclusions are obtained: (1) The observed 3:2 and 2:1 resonant populations are both depleted by a factor of ∼20 relative to model expectations; this depletion is likely due to unmodeled effects, possibly perturbations by other large planetesimals. (2) The size distribution of those KBOs inhabiting the 3:2 resonance is significantly shallower than the Main Belt's size distribution. (3) The total number of KBOs having radii R > 50 km and orbiting interior to Neptune's 2:1 resonance is N ∼ 1.7 × 10 5; these bodies have a total mass of M ∼ 0.08(ρ/1 g cm -3)(p/0.04) -3/2 M ⊕, assumingtheyhaveamaterial density ρ and an albedo p. We also report estimates of the abundances and masses of the Belt's various subpopulations (e.g., the resonant KBOs, the Main Belt, and the so-called Scattered Disk) and provide upper limits on the abundance of Centaurs and Neptune's Trojans, as well as upper limits on the sizes and abundances of hypothetical KBOs that might inhabit the a > 50 AU zone. © 2005. The American Astronomical Society. All rights reserved.
- Kim, J. S., Hines, D. C., Backman, D. E., Hillenbrand, L. A., Meyer, M. R., Rodmann, J., Moro-MartíN, A., Carpenter, J. M., Silverstone, M. D., Bouwman, J., Mamajek, E. E., Wolf, S., Malhotra, R., Pascucci, I., Najita, J., Padgett, D. L., Henning, T., Brooke, T. Y., Cohen, M., , Strom, S. E., et al. (2005). Formation and evolution of planetary systems: Cold outer disks associated with sun-like stars. Astrophysical Journal Letters, 632(1 I), 659-669.More infoAbstract: We present the discovery of debris systems around three Sun-like stars based on observations performed with the Spitzer Space Telescope as part of a Legacy Science Program, "The Formation and Evolution of Planetary Systems" (FEPS). We also confirm the presence of debris around two other stars. All the stars exhibit infrared emission in excess of the expected photospheres in the 70 μm band but are consistent with photospheric emission at ≤33 μm. This restricts the maximum temperature of debris in equilibrium with the stellar radiation to T < 70 K. We find that these sources are relatively old in the FEPS sample, in the age range 0.7-3 Gyr. On the basis of models of the spectral energy distributions, we suggest that these debris systems represent materials generated by collisions of planetesimal belts. We speculate on the nature of these systems through comparisons to our own Kuiper Belt, and on the possible presence of planet(s) responsible for stirring the system and ultimately releasing dust through collisions. We further report observations of a nearby star HD 13974 (d = 11 pc) that are indistinguishable from a bare photosphere at both 24 and 70 μm. The observations place strong upper limits on the presence of any cold dust in this nearby system (L IR/L* 10-5.2). © 2005. The American Astronomical Society. All rights reserved.
- Moro-Martín, A., & Malhotra, R. (2005). Dust outflows and inner gaps generated by massive planets in debris disks. Astrophysical Journal Letters, 633(2 I), 1150-1167.More infoAbstract: Main-sequence stars are commonly surrounded by debris disks, formed by cold far-IR-emitting dust that is thought to be continuously replenished by a reservoir of undetected dust-producing planetesimals. We have investigated the orbital evolution of dust particles in debris disks harboring massive planets. Small dust grains are blown out by radiation pressure, as is well known; in addition, gravitational scattering by the giant planets also creates an outflow of large grains. We describe the characteristics of this large-particle outflow in different planetary architectures and for different particle sizes. In addition, the ejection of particles is responsible for the clearing of dust inside the orbit of the planet. We study the efficiency of particle ejection and the resulting dust density contrast inside and outside the orbit of the planet as a function of the planet's mass and orbital elements and the particle size. We discuss its implications for exoplanetary debris disks and for the interpretation of in situ dust detection experiments on space probes traveling in the outer solar system. © 2005. The American Astronomical Society. All rights reserved.
- Moro-Martín, A., Meyer, M. R., Hillenbrand, L. A., Backman, D. E., Beckwith, S. V., Bouwman, J., Brooke, T. Y., Carpenter, J. M., Cohen, M., Gorti, U., Henning, T., Hines, D. C., Hollenbach, D., Kim, J. S., Lunine, J., Malhotra, R., Mamajek, E. E., Metchev, S., Morris, P., , Najita, J., et al. (2005). The formation and evolution of planetary systems: First results from a spitzer legacy science program. European Space Agency, (Special Publication) ESA SP, 469-470.More infoAbstract: We present 3-160 μm photometry obtained with IRAC and MIPS, spectrophotometry from 5-35 μm using IRS low resolution, and IRS high resolution spectrum of HD 105 (GO V, 30 ± 10 Myr, 40±1 pc) and HD 150706 (G3 V, 700±300 Myr, 27±0.4 pc). For HD 105, possible interpretations include large bodies clearing the dust inside of 45 AU, or a reservoir of gas capable of sculpting the dust distribution. We place preliminary upper limits on the remnant molecular gas. The disk surrounding HD 150706 also exhibits evidence of a large inner hole. Of the four survey targets (0.03-3 Gyr) without previously detected IR excess, the new detection of excess in just one system of intermediate age suggests a variety of initial conditions or divergent evolutionary paths for debris disk systems orbiting solar-type stars.
- Moro-Martín, A., Wolf, S., & Malhotra, R. (2005). Signatures of planets in spatially unresolved debris disks. Astrophysical Journal Letters, 621(2 I), 1079-1097.More infoAbstract: Main-sequence stars are commonly surrounded by debris disks, composed of cold dust continuously replenished by a reservoir of undetected dust-producing planetesimals. In a planetary system with a belt of planetesimals (like the solar system's Kuiper Belt) and one or more interior giant planets, the trapping of dust particles in the mean motion resonances with the planets can create structure in the dust disk, as the particles accumulate at certain semimajor axes. Sufficiently massive planets may also scatter and eject dust particles out of a planetary system, creating a dust-depleted region inside the orbit of the planet. In anticipation of future observations of spatially unresolved debris disks with the Spitzer Space Telescope, we are interested in studying how the structure carved by planets affects the shape of the disk's spectral energy distribution (SED) and consequently whether the SED can be used to infer the presence of planets. We numerically calculate the equilibrium spatial density distributions and SEDs of dust disks originated by a belt of planetesimals in the presence of interior giant planets in different planetary configurations and for a representative sample of chemical compositions. The dynamical models are necessary to estimate the enhancement of particles near the mean motion resonances with the planets and to determine how many particles drift inside the planet's orbit. On the basis of the SEDs and predicted Spitzer colors we discuss what types of planetary systems can be distinguished and the main parameter degeneracies in the model SEDs. © 2005. The American Astronomical Society. All rights reserved.
- Strom, R. C., Malhotra, R., Ito, T., Yoshida, F., & Kring, D. A. (2005). Planetary science: The origin of planetary impactors in the inner solar system. Science, 309(5742), 1847-1850.More infoAbstract: Insights into the history of the inner solar system can be derived from the impact cratering record of the Moon, Mars, Venus, and Mercury and from the size distributions of asteroid populations. Old craters from a unique period of heavy bombardment that ended ∼3.8 billion years ago were made by asteroids that were dynamically ejected from the main asteroid belt, possibly due to the orbital migration of the giant planets. The impactors of the past ∼3.8 billion years have a size distribution quite different from that of the main belt asteroids but very similar to that of near-Earth asteroids.
- Zurbuchen, T. H., Prashant, P., Gallimore, A., Scheeres, D., Murphy, N., Zank, G., Malhotra, R., & Funsten, H. (2005). Interstellar probe: Breakthrough science enabled by nuclear propulsion. IEEE Aerospace Conference Proceedings, 2005.More infoAbstract: 1,2The purpose of Interstellar Probe (ISP) is to follow NASA's exploratory mission to cross the heliospheric boundary regions and, for the first time, enter our extra-solar galactic environment. Interstellar Probe has therefore captured the imagination of the science community and the public for several decades. In 1999, NASA commissioned a science and technology definition team to address the science and technology aspects of ISP. A number of scientific issues and technology aspects have changed. We now also have modern three-dimensional simulations of the heliospheric interface regions. In addition, nuclear power has become a feasible alternative for propulsion of Interstellar Probe. We discuss how nuclear propulsion might affect the instrumentation, mission requirements, and mission plan, as well as how it may enable new science objectives. We discuss the science, payload, ongoing trade studies, and development of this approach for the Interstellar Probe, relying on technology developed for the Jupiter Icy Moon Orbiter (JIMO). © 2005 IEEE.
- Zurbuchen, T. H., Prashant, P., Gallimore, A., Scheeres, D., Murphy, N., Zank, G., Malhotra, R., & Funsten, H. (2005). Interstellar probe: Breakthrough science enabled by nuclear propulsion. Space Technology, 25(3-4), 179-187.More infoAbstract: It is the purpose of Interstellar Probe (ISP) to follow NASA's exploratory mission to cross the heliospheric boundary regions and, for the first time, enter our extra-solar galactic environment. Interstellar Probe has therefore captured the imagination of the science community and the public for several decades. In 1999, NASA commissioned a science and technology definition team to address the science and technology aspects of ISP. However, a number of scientific issues and technology aspects have changed: Voyager has now observed signatures of the heliosphere's termination shock. We now also have modern three-dimensional simulations of the heliospheric interface regions. In addition, nuclear power has become a feasible alternative for propulsion of Interstellar Probe. We will discuss how nuclear propulsion might affect the instrumentation, mission requirements, and the mission plan, as well as how it may enable new science objectives. We will also discuss the science, payload, ongoing trade studies, and development of this approach for the Interstellar Probe, relying on technology developed for the Jupiter Icy Moon Orbiter (JIMO). © 2005 Published by Lister Science.
- Bernstein, G. M., Trilling, D. E., Allen, R. L., Brown, M. E., Holman, M., & Malhotra, R. (2004). The size distribution of trans-Neptunian bodies. Astronomical Journal, 128(3 1785), 1364-1390.More infoAbstract: We search 0.02 deg2 of the invariable plane for trans-Neptunian objects (TNOs) 25 AU or more distant using the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. With 22 ks per pointing, the search is more than 50% complete for m606w ≤ 29.2. Three new objects are discovered, the faintest with mean magnitude m = 28.3 (diameter ≈25 km), which is 3 mag fainter than any previously well-measured solar system body. Each new discovery is verified with a follow-up 18 ks observation with the ACS, and the detection efficiency is verified with implanted objects. The three detections are a factor of ∼25 less than would be expected under extrapolation of the power-law differential sky density for brighter objects, Σ(m) ≡ dN / dm dΩ α 10α m with α ≈ 0.63. Analysis of the ACS data and recent TNO surveys from the literature reveals departures from this power law at both the bright and faint ends. Division of the TNO sample by distance and inclination into "classical Kuiper belt" (CKB) and "Excited" samples reveals that Σ(m) differs for the two populations at 96% confidence, and both samples show departures from power-law behavior. A double power-law Σ(m) adequately fits all data. Implications of these departures include the following: (1) The total mass of the "classical" Kuiper belt is ≈0.010 M⊕, only a few times Pluto's mass, and is predominantly in the form of ∼-100 km bodies (barring a secondary peak in the mass distribution at sub-10 km sizes). The mass of Excited objects is perhaps a few times larger. (2) The Excited class has a shallower bright-end magnitude (and, presumably, size) distribution; the largest objects, including Pluto, make up tens of percent of the total mass whereas the largest CKB objects are only ∼-2% of its mass. (3) The derived size distributions predict that the largest Excited body should be roughly the mass of Pluto, and the largest CKB body should have mR ≈ 20-hence, Pluto is feasibly considered to have originated from the same physical process as the Excited TNOs. (4) The observed deficit of small TNOs occurs in the size regime where present-day collisions are expected to be disruptive, suggesting extensive depletion by collisions. The Excited and CKB size distributions are qualitatively similar to some numerical models of growth and erosion, with both accretion and erosion appearing to have proceeded to more advanced stages in the Excited class than in the CKB. (5) The lack of detections of distant TNOs implies that if a mass of TNOs comparable to the CKB is present near the invariable plane beyond 50 AU, that distant population must be composed primarily of bodies smaller than ≈40 km. (6) There are too few small CKB objects for this population to be the reservoir of Jupiter-family comet precursors without a significant upturn in the population at diameters under 20 km. With optimistic model parameters and extrapolations, the Excited population could be the source reservoir. Implications of these discoveries for the formation and evolution of the outer solar system are discussed.
- Kortenkamp, S. J., Malhotra, R., & Michtchenko, T. (2004). Survival of Trojan-type companions of Neptune during primordial planet migration. Icarus, 167(2), 347-359.More infoAbstract: We investigate the survivability of Trojan-type companions of Neptune during primordial radial migration of the giant planets Jupiter, Saturn, Uranus, and Neptune. We adopt the usual planet migration model in which the migration speed decreases exponentially with a characteristic time scale τ (the e-folding time). We perform a series of numerical simulations, each involving the migrating giant planets plus ∼ 1000 test particle Neptune Trojans with initial distributions of orbital eccentricity, inclination, and libration amplitude similar to those of the known jovian Trojans asteroids. We analyze these simulations to measure the survivability of Neptune's Trojans as a function of migration rate. We find that orbital migration with the characteristic time scale τ = 106 years allows about 35% of preexisting Neptune Trojans to survive to 5τ, by which time the giant planets have essentially reached their final orbits. In contrast, slower migration with τ = 107 years yields only a ∼ 5% probability of Neptune Trojans surviving to a time of 5τ. Interestingly, we find that the loss of Neptune Trojans during planetary migration is not a random diffusion process. Rather, losses occur almost exclusively during discrete prolonged episodes when Trojan particles are swept by secondary resonances associated with mean-motion commensurabilities of Uranus with Neptune. These secondary resonances arise when the circulation frequencies, f, of critical arguments for Uranus-Neptune mean-motion near-resonances (e.g., f1:2UN, f4:7UN) are commensurate with harmonics of the libration frequency of the critical argument for the Neptune-Trojan 1:1 mean-motion resonance (f1:1NT). Trojans trapped in the secondary resonances typically have their libration amplitudes amplified until they escape the 1:1 resonance with Neptune. Trojans with large libration amplitudes are susceptible to loss during sweeping by numerous high-order secondary resonance (e.g., f1:2UN ≈ 11f1:1NT). However, for the slower migration, with τ = 107 years, even tightly bound Neptune Trojans with libration amplitudes below 10° can be lost when they become trapped in 1:3 or 1:2 secondary resonances between f1:2UN and f1:1NT. With τ = 107 years the 1:2 secondary resonance was responsible for the single greatest episode of loss, ejecting nearly 75% of existing Neptune Trojans. This episode occurred during the late stages of planetary migration when the remnant planetesimal disk would have been largely dissipated. We speculate that if the number of bodies liberated during this event was sufficiently high they could have caused a spike in the impact rate throughout the Solar System. © 2003 Elsevier Inc. All rights reserved.
- Meyer, M. R., Hillenbrand, L. A., Backman, D. E., Beckwith, S. V., Bouwman, J., Brooke, T. Y., Carpenter, J. M., Cohen, M., Gorti, U., Henning, T., Hines, D. C., Hollenbach, D., Kim, J. S., Lunine, J., Malhotra, R., Mamajek, E. E., Metchev, S., Moro-Martin, A., Morris, P., , Najita, J., et al. (2004). The formation and evolution of planetary systems: First results from a Spitzer legacy science program. Astrophysical Journal, Supplement Series, 154(1), 422-427.More infoAbstract: We present 3-160 μm photometry obtained with the Infrared Array Camera (IRAC) and Multiband Imaging Photometer for Spitzer (MIPS) instruments for the first five targets from the Spitzer Space Telescope Legacy Science Program "Formation and Evolution of Planetary Systems" and 4-35 μm spectrophotometry obtained with the Infrared Spectrograph (IRS) for two sources. We discuss in detail our observations of the debris disks surrounding HD 105 (G0 V, 30 ± 10 Myr) and HD 150706 (G3 V, ∼700 ± 300 Myr). For HD 105, possible interpretations include large bodies clearing the dust inside of 45 AU or a reservoir of gas capable of sculpting the dust distribution. The disk surrounding HD 150706 also exhibits evidence of a large inner hole in its dust distribution. Of the four survey targets without previously detected IR excess, spanning ages 30 Myr to 3 Gyr, the new detection of excess in just one system of intermediate age suggests a variety of initial conditions or divergent evolutionary paths for debris disk systems orbiting solar-type stars.
- Michtchenko, T. A., & Malhotra, R. (2004). Secular dynamics of the three-body problem: Application to the υ Andromedae planetary system. Icarus, 168(2), 237-248.More infoAbstract: The discovery of extra-solar planetary systems with multiple planets in highly eccentric orbits (∼ 0.1-0.6), in contrast with our own Solar System, makes classical secular perturbation analysis very limited. In this paper, we use a semi-numerical approach to study the secular behavior of a system composed of a central star and two massive planets in co-planar orbits. We show that the secular dynamics of this system can be described using only two parameters, the ratios of the semi-major axes and the planetary masses. The main dynamical features of the system are presented in geometrical pictures that allows us to investigate a large domain of the phase space of this three-body problem without time-expensive numerical integrations of the equations of motion, and without any restriction on the magnitude of the planetary eccentricities. The topology of the phase space is also investigated in detail by means of spectral map techniques, which allow us to detect the separatrix of a non-linear secular apsidal resonance. Finally, the qualitative study is supplemented by direct numerical integrations. Three different regimes of secular motion with respect to the secular angle Δ̄ω are possible: they are circulation, oscillation (around 0° and 180°), and high eccentricity libration in a non-linear secular resonance. The first two regimes are a continuous extension of the classical linear secular perturbation theory; the last is a new feature, hitherto unknown, in the secular dynamics of the three-body problem. We apply the analysis to the case of the two outer planets in the v Andromedae system, and obtain its periodic and ordinary orbits, the general structure of its secular phase space, and the boundaries of its secular stability; we find that this system is secularly stable over a large domain of eccentricities. Applying this analysis to a wide range of planetary mass and semi-major axis ratios (centered about the v Andromedae parameters), we find that apsidal oscillation dominates the secular phase space of the three-body coplanar system, and that the non-linear secular resonance is also a common feature. © 2004 Elsevier Inc. All rights reserved.
- Yoshida, F., Dermawan, B., Ito, T., Sawabe, Y., Haji, M., Saito, R., Hirai, M., Nakamura, T., Sato, Y., Yanagisawa, T., & Malhotra, R. (2004). Photometric observations of a very young family-member asteroid (832) Karin. Publications of the Astronomical Society of Japan, 56(6), 1105-1113.More infoAbstract: The asteroid (832) Karin is the largest member of the Karin family, which is thought to have been formed by a catastrophic collision 5.8 Myr ago. We performed photometric observations of Karin from 2003 July to September, and we report here on its lightcRurve and colors in several visible bands. The rotational synodic period of Karin was determined to be 18.35 ± 0.02 hr. Its absolute magnitude (H) and the slope parameter (G) of the solar phase curve were 11.49 ± 0.02 and 0.19 ± 0.04, respectively. Based on our color observations, we confirmed that Karin is an S-type asteroid. In addition, we found that there is likely to be a color variation over the surface of Karin. We infer that the color variation is due to the difference between the fresh surface, excavated by the family-forming disruption, and the weathered surface, exposed to space radiation and particle bombardment over a long period.
- Zurbuchen, T. H., Prashant, P., Gallimore, A., Scheeres, D., Murphy, N., Zank, G., Malhotra, R., & Funsten, H. (2004). Interstellar probe: Breakthrough science enabled by nuclear propulsion. International Astronautical Federation - 55th International Astronautical Congress 2004, 4, 2736-2746.More infoAbstract: It is the purpose of Interstellar Probe (ISP) to follow NASA's exploratory mission to cross the heliospheric boundary regions and, for the first time, enter our extra-solar galactic environment. Interstellar Probe has therefore captured the imagination of the science community and the public for several decades. In 1997, NASA commissioned a science and technology definition team to address the science and technology aspects of ISP. However, a number of scientific issues and technology aspects have changed: Voyager has now observed signatures of the heliosphere's termination shock. We now also have modern three-dimensional simulations of the heliospheric interface regions. In addition, nuclear power has become a feasible alternative for propulsion of Interstellar Probe. We intend to discuss cross-disciplinary opportunities for scientific studies of the outer solar system and astrophysics, in an effort to broaden the scope and impact of the ISP mission. We will also discuss how nuclear propulsion might affect the instrumentation, mission requirements, and the mission plan, as well as how it may enable new science objectives. We discuss the science, payload, ongoing trade studies, and development of this approach for the Interstellar Probe, relying on technology developed for the Jupiter Icy Moon Orbiter (JIMO).
- Backman, D., Beckwith, S., Carpenter, J., Cohen, M., Henning, T., Hillenbrand, L., Hines, D., Hollenbach, D., Lunine, J., Malhotra, R., Meyer, M., Najita, J., Padgett, D., Soderblom, D., Stauffer, J., Strom, S., Watson, D., Weidenschilling, S., Young, E., & Morris, P. (2003). The formation and evolution of planetary systems: Placing our solar system in context. European Space Agency, (Special Publication) ESA SP, 349-354.More infoAbstract: The spectrophotometric observations of solar system were studied to provide an astronomical context for understanding the solar system. Investigations show that the mid-infrared spectroscopic observations were sensitive to dust particles, which in turn probe the physical conditions in the disk. Data was collected to realize the fundamental limits imposed by the instrument stability and systematic calibration uncertainities. The results show the measurement of mean properties of the evolving dust disks, and the measurement of various evolutionary paths related to stellar properties.
- Moro-Martín, A., & Malhotra, R. (2003). Dynamical models of Kuiper belt dust in the inner and outer solar system. Astronomical Journal, 125(4 1768), 2255-2265.More infoAbstract: We report several results related to the dynamical evolution of dust produced in the Kuiper belt (KB). We show that its particle size frequency distribution in space is greatly changed from the distribution at production, as a result of the combined effects of radiation forces and the perturbations of the planets. We estimate the contribution of KB dust to the zodiacal cloud by calculating the radial profile of its number density near the ecliptic. We also study the contribution of KB dust to the population of interplanetary dust particles (IDPs) collected at Earth, by calculating geocentric encounter velocities and capture rates. Our models show, in contrast with previous studies, that KB dust grains on Earth-crossing orbits have high eccentricities and inclinations and, therefore, that their encounter velocities are similar to those of cometary grains and not asteroidal grains. We estimate that at most 25% in number of captured IDPs have a cometary or KB origin; the KB contribution may be as low as 1%-2%. We present the velocity field of KB dust throughout the solar system; this, together with the number density radial profile, is potentially useful for planning spacecraft missions to the outer solar system.
- Tiscareno, M. S., & Malhotra, R. (2003). The dynamics of known centaurs. Astronomical Journal, 126(6 1776), 3122-3131.More infoAbstract: We have numerically investigated the long-term dynamical behavior of known Centaurs. This class of objects is thought to constitute the transitional population between the Kuiper belt and the Jupiter-family comets (JFCs). In our study, we find that over their dynamical lifetimes these objects diffuse into the JFCs and other sinks, and they also make excursions into the scattered disk, but (not surprisingly) do not diffuse into the parameter space representing the main Kuiper belt. These Centaurs spend most of their dynamical lifetimes in orbits of eccentricity 0.2-0.6 and perihelion distance 12-30 AU. Their orbital evolution is characterized by frequent close encounters with the giant planets. Most of these Centaurs will escape from the solar system (or enter the Oort cloud), while a fraction will enter the JFC population and a few percent will impact a giant planet. Their median dynamical lifetime is 9 Myr, although there is a wide dispersion in lifetimes, ranging from less than 1 Myr to more than 100 Myr. We find the dynamical evolution of this sample of Centaurs to be less orderly than the planet-to-planet "handoff" described in previous investigations. We discuss the implications of our study for the spatial distribution of the Centaurs as a whole.
- Allen, R. L., Bernstein, G. M., & Malhotra, R. (2002). Observational limits on a distant cold Kuiper belt. Astronomical Journal, 124(5 1763), 2949-2954.More infoAbstract: Almost all the more than 500 known Kuiper belt objects (KBOs) have been discovered within 50 AU of the Sun. One possible explanation for the observed lack of KBOs beyond 50 AU is that the distant Kuiper belt is dynamically very cold and thus thin enough on the sky to have slipped between previous deep survey fields. We have completed a survey designed to search for a dynamically cold distant Kuiper belt near the invariable plane of the solar system. In 2.3 deg2 we have discovered a total of 33 KBOs and 1 Centaur, but no objects in circular orbits beyond 50 AU. We find that we can exclude at 95% CL the existence of a distant disk inclined by i ≤ 1° to the invariable plane and containing more than 1.2 times as many D > 185 km KBOs between 50 and 60 AU as the observed inner Kuiper belt, if the distant disk is thinner than σ = 1°.75.
- Malhotra, R. (2002). A dynamical mechanism for establishing apsidal resonance. Astrophysical Journal Letters, 575(1 II), L33-L36.More infoAbstract: We show that in a system of two planets initially in nearly circular orbits, an impulse perturbation that imparts a finite eccentricity to one planet's orbit causes the other planet's orbit to become eccentric as well and also naturally results in a libration of their relative apsidal longitudes for a wide range of initial conditions. We suggest that such a mechanism may explain orbital eccentricities and apsidal resonance in some exoplanetary systems. The eccentricity impulse could be caused by the ejection of a planet from these systems or by torques from a primordial gas disk. The amplitude of secular variations provides an observational constraint on the dynamical history of such systems.
- Moro-Martín, A., & Malhotra, R. (2002). A study of the dynamics of dust from the Kuiper belt: Spatial distribution and spectral energy distribution. Astronomical Journal, 124(4 1762), 2305-2321.More infoAbstract: The dust produced in the Kuiper belt (KB) spreads throughout the solar system, forming a dust disk. We numerically model the orbital evolution of KB dust and estimate its equilibrium spatial distribution and its brightness and spectral energy distribution (SED), assuming graybody absorption and emission by the dust grains. We show that the planets modify the KB disk SED, so potentially we can infer the presence of planets in spatially unresolved debris disks by studying the shape of their SEDs. We point out that there are inherent uncertainties in the prediction of structure in the dust disk, owing to the chaotic dynamics of dust orbital evolution imposed by resonant gravitational perturbations of the planets.
- Allen, R. L., Bernstein, G. M., & Malhotra, R. (2001). The edge of the solar system. Astrophysical Journal Letters, 549(2 PART 2), L241-L244.More infoAbstract: We have surveyed for Kuiper Belt objects (KBOs) in six fields of the ecliptic (total sky area 1.5 deg2) to limiting magnitudes between R = 24.9 and R = 25.9. This is deep enough to detect KBOs of diameter ≳ 160 km at a distance of 65 AU. We detected 24 objects. None of these objects, however, is beyond 53 AU. Our survey places a 95% CL upper limit of Σ < 5 deg-2 on the surface density of KBOs larger than ∼160 km beyond 55 AU. This can be compared to the surface density of ∼6 deg-2 of ≥ 160 km KBOs at distances 30-50 AU determined from this survey and previous shallower surveys. The mean volume density of D > 160 km KBOs in the 55-65 AU region is, at greater than 95% confidence, less than the mean density in the 30-50 AU region, and at most two-thirds of the mean density from 40 to 50 AU. Thus, a substantial density increase beyond 50 AU is excluded in this model-independent estimate. A dense primordial disk could be present beyond 50 AU if it contains only smaller objects or is sufficiently thin and inclined to have escaped detection in our six survey fields.
- Malhotra, R., Holman, M., & Ito, T. (2001). Chaos and stability of the solar system. Proceedings of the National Academy of Sciences of the United States of America, 98(22), 12342-12343.More infoPMID: 11606772;PMCID: PMC60054;Abstract: Over the last two decades, there has come about a recognition that chaotic dynamics is pervasive in the solar system. We now understand that the orbits of small members of the solar system-asteroids, comets, and interplanetary dust-are chaotic and undergo large changes on geological time scales. Are the major planets' orbits also chaotic? The answer is not straightforward, and the subtleties have prompted new questions.
- Stepinski, T. F., Malhotra, R., & Black, D. C. (2000). The υ Andromedae system: Models and stability. Astrophysical Journal Letters, 545(2 PART 1), 1044-1057.More infoAbstract: Radial velocity observations of the F8 V star υ Andromedae taken at Lick and at Whipple Observatories have revealed evidence of three periodicities in the line-of-sight velocity of the star. These periodicities have been interpreted as evidence for at least three low-mass companions (LMCs) revolving around υ Andromedae. The mass and orbital parameters inferred for these companions raise questions about the dynamical stability of the system. We report here results from our independent analysis of the published radial velocity data, as well as new unpublished data taken at Lick Observatory. Our results confirm the finding of three periods in the data. Our best fits to the data, on the assumption that these periods arise from the gravitational perturbations of companions in Keplerian orbits, are also generally in agreement but with some differences from the earlier findings. We find that the available data do not constrain well the orbital eccentricity of the middle companion in a three-companion model of the data. We also find that in order for our best-fit model to the Lick data to be dynamically stable over the lifetime of the star (∼ 2 billion years), the system must have a mean inclination to the plane of the sky greater than 13°. The corresponding minimum inclination for the best fit to the Whipple data set is 19°. These values imply that the maximum mass for the outer companion can be no greater than about 20 Jupiter masses. Our analysis of the stability of the putative systems also places constraints on the relative inclinations of the orbital planes of the companions. We comment on global versus local (i.e., method of steepest descent) means of finding best-fit orbits from radial velocity data sets.
- Hahn, J. M., & Malhotra, R. (1999). Orbital evolution of planets embedded in a planetesimal disk. Astronomical Journal, 117(6), 3041-3053.More infoAbstract: The existence of the Oort comet cloud, the Kuiper belt, and plausible inefficiencies in planetary core formation all suggest that there was once a residual planetesimal disk of mass ∼ 10-100 M⊕ in the vicinity of the giant planets following their formation. Since removal of this disk requires an exchange of orbital energy and angular momentum with the planets, significant planetary migration can ensue. The planet migration phenomenon is examined numerically by evolving the orbits of the giant planets while they are embedded in a planetesimal disk having a mass of MD = 10-200 M⊕. We find that Saturn, Uranus, and Neptune evolve radially outward as they scatter the planetesimals, while Jupiter's orbit shrinks as it ejects mass. Higher mass disks result in more rapid and extensive planet migration. If orbital expansion and resonance trapping by Neptune are invoked to explain the eccentricities of Pluto and its cohort of Kuiper belt objects at Neptune's 3:2 mean motion resonance, then our simulations suggest that a disk mass of order MD ∼ 50 M⊕ is required to expand Neptune's orbit by Δa ∼ 7 AU, in order to pump up Plutino eccentricities to e ∼ 0.3. Such planet migration implies that the solar system was more compact in the past, with the initial Jupiter-Neptune separation having been smaller by about 30%. We discuss the fate of the remnants of the primordial planetesimal disk. We point out that most of the planetesimal disk beyond Neptune's 2:1 resonance should reside in nearly circular, low-inclination orbits, unless there are (or were) additional, unseen, distant perturbers. The planetesimal disk is also the source of the Oort cloud of comets. Using the results of our simulations together with a simple treatment of Oort cloud dynamics, we estimate that ∼ 12 M⊕ of disk material was initially deposited in the Oort cloud, of which ∼ 4 M⊕ will persist over the age of the solar system. The majority of these comets originated from the Saturn-Neptune region of the solar nebula.
- Malhotra, R. (1999). Chaotic planet formation. Nature, 402(6762), 599-600.
- Liou, J., & Malhotra, R. (1997). Depletion of the outer asteroid belt. Science, 275(5298), 375-377.More infoAbstract: During the early history of the solar system, it is likely that the outer planets changed their distance from the sun, and hence, their influence on the asteroid belt evolved with time The gravitational influence of Jupiter and Saturn on the orbital evolution of asteroids in the outer asteroid belt was calculated. The results show that the sweeping of mean motion resonances associated with planetary migration efficiently destabilizes orbits in the outer asteroid belt on a time scale of 10 million years. This mechanism provides explanation for the observed depletion of asteroids in that region.
- Malhotra, R. (1997). Galileo results raise new questions about Ganymede. Physics World, 10(3), 21-22.
- Malhotra, R. (1996). The phase space structure near Neptune resonances in the Kuiper Belt. Astronomical Journal, 111(1), 504-516.More infoAbstract: The Solar system beyond Neptune is believed to house a population of small primordial bodies left over from the planet formation process. The region up to heliocentric distance ∼50 AU (a.k.a. the Kuiper Belt) may be the source of the observed short-period comets. In this region, the phase space structure near orbital resonances with Neptune is of special interest for the long-term stability of orbits. There is reason to believe that a significant fraction (perhaps most) of the Kuiper Belt objects reside preferentially in these resonance locations. This paper describes the dynamics of small objects near the major orbital resonances with Neptune. Estimates of the widths of stable resonance zones as well as the properties of resonant orbits are obtained from the circular, planar restricted three-body model. Although this model does not contain the full complexity of the long-term orbital dynamics of Kuiper Belt objects subject to the full N-body perturbations of all the planets, it does provide a baseline for the phase space structure and properties of resonant orbits in the trans-Neptunian Solar system. © 1996 American Astronomical Society.
- Malhotra, R. (1995). The origin of Pluto's orbit: Implications for the solar system beyond Neptune. Astronomical Journal, 110(1), 420-429.More infoAbstract: The origin of the highly eccentric, inclined, and resonance-locked orbit of Pluto has long been a puzzle. A possible explanation has been proposed recently [Malhotra, 1993, Nature, 365, 819] which suggests that these extraordinary orbital properties may be a natural consequence of the formation and early dynamical evolution of the outer solar system. A resonance capture mechanism is possible during the clearing of the residual planetesimal debris and the formation of the Oort Cloud of comets by planetesimal mass loss from the vicinity of the giant planets. If this mechanism were in operation during the early history of the planetary system, the entire region between the orbit of Neptune and approximately 50 AU would have been swept by first-order mean motion resonances. Thus, resonance capture could occur not only for Pluto, but quite generally for other trans-Neptunian small bodies. Some consequences of this evolution for the present-day dynamical structure of the trans-Neptunian region are (i) most of the objects in the region beyond Neptune and up to ∼50 AU exist in very narrow zones located at orbital resonances with Neptune (particularly the 3:2 and the 2:1 resonances); and (ii) these resonant objects would have significantly large eccentricities. The distribution of objects in the Kuiper Belt as predicted by this theory is presented here.
- Malhotra, R. (1994). A mapping method for the gravitational few-body problem with dissipation. Celestial Mechanics & Dynamical Astronomy, 60(3), 373-385.More infoAbstract: Recently a new class of numerical integration methods - "mixed variable symplectic integrators" - has been introduced for studying long-term evolution in the conservative gravitational few-body problem. These integrators are an order of magnitude faster than conventional ODE integration methods. Here we present a simple modification of this method to include small non-gravitational forces. The new scheme provides a similar advantage of computational speed for a larger class of problems in Solar System dynamics. © 1994 Kluwer Academic Publishers.
- Malhotra, R. (1994). Nonlinear resonances in the solar system. Physica D: Nonlinear Phenomena, 77(1-3), 289-304.More infoAbstract: Orbital resonances are ubiquitous in the Solar system. They play a decisive role in the long term dynamics, and in some cases the physical evolution, of the planets and of their natural satellites, as well as the evolution of small bodies (including dust) in the planetary system. The few-body gravitational problem of hierarchical planetary-type systems allows for a complex range of dynamical timescales, from the fast orbital periods to the very slow orbit precession rates. The interaction of fast and slow degrees of freedom produces a rich diversity of resonance phenomena. Weak dissipative effects - such as tides or radiation drag forces - also produce unexpectedly rich dynamical behaviors. This paper provides a mostly qualitative discussion of simple dynamical models for the commonly encountered orbital resonance phenomena in the Solar system. © 1994.
- Malhotra, R. (1993). Orbital Resonances in the Solar Nebula: Strengths and Weaknesses. Icarus, 106(1), 264-273.More infoAbstract: A planetesimal moving in the Solar Nebula experiences an aerodynamic drag which causes its orbit to circularize and shrink. However, resonant perturbations from a protoplanet interior to the planetesimal's orbit can counteract both the orbital decay and the damping of the eccentricity: the planetesimal can be captured into an orbital resonance and its eccentricity pumped up to a modestly high equilibrium value. Thus, orbital resonances constitute (partial) barriers to the delivery of planetesimals into the feeding zone of the protoplanet. We have established the characteristics of the phenomenon of resonance capture by gas drag in the circular restricted three-body approximation. We have determined the strengths of the equilibrium resonant orbits with respect to impulsive velocity perturbations. We conclude that planetesimals captured in orbital resonances are quite vulnerable to being dislocated from these orbits by mutual planetesimal interactions, but that the resonances are effective in slowing down the rate of orbital decay of planetesimals. Only very small bodies, ≤100 m, are able to reach a ∼ 1M⊕ protoplanet without being slowed down by resonances. © 1993 Academic Press. All rights reserved.
- Malhotra, R. (1993). The origin of Pluto's peculiar orbit. Nature, 365(6449), 819-X.More infoAbstract: THE origin of Pluto's unusual orbit - the most eccentric and inclined of all the planets - remains a mystery. The orbits of Pluto and Neptune overlap, but close approaches of these two planets are prevented by the existence of a resonance condition1: Pluto's orbital period is exactly 3/2 that of Neptune, which ensures that the conjunctions always occur near Pluto's aphelion. Long-term orbit integrations2-5 have uncovered other subtle resonances and near-resonances, and indicate that Pluto's orbit is chaotic yet remains macroscopically stable over billion-year timescales. A suggestion4 that the orbit may have evolved purely by chaotic dynamics appears unlikely in light of recent orbital stability studies6, unless one appeals to a well-timed collision to place Pluto in its stable orbit19. Here I show that Pluto could have acquired its current orbit during the late stages of planetary accretion, when the jovian planets underwent significant orbital migration as a result of encounters with residual planetesimals7. As Neptune moved outwards, a small body like Pluto in an initially circular orbit could have been captured into the 3:2 resonance, following which its orbital eccentricity would rise rapidly to its current Neptune-crossing value.
- Malhotra, R. (1993). Three-body effects in the PSR 1257+12 planetary system. Astrophysical Journal Letters, 407(1), 266-275.More infoAbstract: We present a detailed theoretical analysis of the three-body effects in the putative planetary system of PSR 1257+12. We discuss how these effects are manifested in the pattern of pulse arrival times; the dominant perturbation can be described as a modulation of the phases of the near-sinusoidal signals of the two planetary companions. We provide explicit formulas for the time dependence of the osculating orbital elements that are needed for an improved timing model for this system. If a timing model with fixed, independent Keplerian orbits continues to be used for the timing analysis, and if two planets are indeed orbiting this pulsar, then the three-body effects should become detectable by means of a growth in the postfit residuals as more observations are accumulated. If the typical error in the pulse arrival time measurements is ∼ 10 μs, the amplitude of the postfit residuals will increase beyond this level with three to five years of timing observations. Their detection will place the planetary interpretation on firmer ground, and the improved timing model will yield the orbital inclinations and the masses of the planets relative to the mass of the pulsar. An absence of this signal will make the presence of these planets highly unlikely.
- Malhotra, R., Black, D., Eck, A., & Jackson, A. (1992). Resonant orbital evolution in the putative planetary system of PSR1257+12. Nature, 356(6370), 583-585.More infoAbstract: PERIODIC variations in the arrival times of pulses from the millisecond pulsar PSR1257+12 are most straightforwardly interpreted as indicating the presence of two planet-like companions orbiting the pulsar1. Rasio et al.2 have proposed that the planetary explanation is amenable to a simple test: the deduced parameters put the planets near an orbital resonance, in which case secular evolution of the orbits should be observable in a matter of years. Detection of such orbital evolution would yield the masses and orbital inclinations of the planets. Here we point out that if the masses of the two planets are more than ∼10 times greater than the minimum values (3.4 and 2.8 Earth masses) allowed by the observations, then their orbits will be in an exact 3:2 resonance. The character of the predicted orbital parameter perturbations is then markedly different from the periodic perturbations that result from only a near-resonance. The amplitude of the perturbations is much greater, and is very sensitive to the planet masses.
- Malhotra, R. (1991). Tidal origin of the Laplace resonance and the resurfacing of Ganymede. Icarus, 94(2), 399-412.More infoAbstract: I present a new scenario for the tidal origin of the Laplace resonance. The inner three Galilean satellites are supposed to have formed in orbits well away from the 2/1 pair-wise mean motion commensurabilities and the three body Laplace resonance. The dynamics is controlled by the evolution of the 2/1 critical frequencies, ω1 = 2n2 - n1 and ω2 = 2n3 - n2, where n1, n2, n3 are the mean motions of Io, Europa, and Ganymede. I show that the Laplace relation, ω1 = ω2, may have been established from within a previous three body resonance defined by ω1 ω2 ≈ 1 2. The ω1 ω2 ≈ 1 2 resonance would have excited Ganymede's orbital eccentricity to a high value. The attendant enhanced tidal heating in Ganymede during that high eccentricity period provides a possible explanation for the geologically younger surface of Ganymede compared to that of its "twin satellite," Callisto. The extent of orbital evolution required for this scenario is easily accomodated by values of QJ of several times 105. © 1991.
- Dermott, S. F., Nicholson, P. D., Gomes, R. S., & Malhotra, R. (1990). Modelling the IRAS solar system dust bands. Advances in Space Research, 10(3-4), 171-180.More infoAbstract: The chief difficulties in interpreting the geometry of the IRAS solar system dust bands are (1) the geocentric viewpoint of the IRAS telescope and (2) the large range of elongation angles sampled by IRAS. To overcome these and other difficulties we have a constructed a three-dimensional numerical model that permits the calculation of the latitudinal distribution of the thermal flux that would be received at the Earth from any particular distribution of dust particle orbits. The model includes the effects of planetary perturbations on the dust particle orbits, reproduces the exact viewing geometry of the IRAS telescope, and allows for the eccentricity of the Earth's orbit. The result is a model for the variation with ecliptic latitude of the brightness observed in a given waveband as the line of sight of the telescope sweeps through the model dustband at a constant elongation angle. Models based on the Hirayama asteroid families are compared with the IRAS observations. © 1989.
- Malhotra, R. (1990). Capture probabilities for secondary resonances. Icarus, 87(2), 249-264.More infoAbstract: Secondary resonances are commensurabilities between the libration and circulation frequencies of two neighboring mean motion resonances. We present a general analysis of secondary resonances within a perturbed pendulum model. There exists a self-similarity between secondary resonances and primary resonances which is made apparent in this analysis. We derive formulas for the probability of capture into secondary resonances by making use of J. Henrard's (1982, Celest. Mech. 27, 3-22) theory for separatrix crossing transitions. The importance of secondary resonances in long-time evolutions has been discovered in several recent studies of orbital dynamics problems in the solar system. We apply the theory developed here to the tidal evolution of Miranda and Umbriel in the 1:3 iM2 resonance and find significant probabilities of capture into secondary resonances. Our analytical estimates are consistent with previous numerical results, and support the scenario that tidal capture into the 1:3 iM2 resonance followed by disruption of the resonance due to capture into a secondary resonance provides an explanation for the anomalously large orbital inclination (4.3°) of Miranda. © 1990.
- Malhotra, R., & Dermott, S. F. (1990). The role of secondary resonances in the orbital history of Miranda. Icarus, 85(2), 444-480.More infoAbstract: We have investigated in some detail the role of secondary resonances in the tidal evolution of Miranda and Umbriel through the 1:3 mean motion commensurability. The constraints placed by the present values of the orbital elements narrow the investigations to the IM2, eMeU, and the eM2 primary resonances. Tidal evolution in any of these primary resonances is described well by the analytical single resonance theory up to the point when a low-order secondary resonance is encountered. (A secondary resonance arises when the libration frequency of a primary resonance is commensurate with the circulation frequency of a nearby primary resonance). We present a simple "perturbed-pendulum" model to understand the origin and dynamics of these secondary resonances. Capture into a secondary resonance leads to chaotic motion and the eventual disruption of the primary mean motion resonance. In order to study the long-time evolution, we have used two approaches to speed up the computations: frequency scaling and algebraic mappings. We find that although several important features of the dynamics of the primary resonances are invariant under frequency scaling, certain other phenomena associated with secondary resonances are not. Since these phenomena are crucial to the dynamics, the numerical integration of the full equations of motion with frequency scaling is inadequate for our purpose. Therefore, we have relied primarily on the use of algebraic mappings in our numerical studies. We show that the present value (4.34°) of Miranda's orbital inclination is probably the result of capture into the IM2 primary resonance and subsequent capture into the 3 1 secondary resonance. We also find that there is a 10-20% probability that the eccentricity-type primary resonances could have increased Miranda's orbital eccentricity to values as high as 0.035, which would persist after the disruption of the mean motion commensurability. Damping of an eccentricity as high as 0.035 due to tidal dissipation in the satellite could help explain the bizarre surface features on Miranda. © 1990.
- Dermott, S. F., Malhotra, R., & Murray, C. D. (1988). Dynamics of the Uranian and Saturnian satelite systems: A chaotic route to melting Miranda?. Icarus, 76(2), 295-334.More infoAbstract: We argue that the anomalously large inclination of Miranda, the postaccretional resurfacing of both Miranda and Ariel, and the anomalously large eccentricities of the inner Uranian satellites indicate that resonant configurations once existed in the Uranian satellite system that have been since disrupted. Similar anomalies that cannot be accounted for by the present resonant configurations also exist in the Saturnian satellite system, and we suggest that temporary resonances existed in the past in that system as well. Using classical methods of analyzing the dynamics of resonance, we show how temporary capture into a second- or higher-order resonance can produce large increases in e and I on comparatively short time scales. However, these methods may not provide a complete description of resonances in the Uranian satellite system. Since values of J2( Rp a)2 for the inner Uranian satellites are small while their mass ratios, m M, are large, resonances in the Uranian system are not always well separated. For resonances that are not well separated, it is not possible to analyzed the dynamics using a disturbing function that is truncated to the extent that it contains only a single resonant argument. We have made some progress with this problem using the Cornell National Supercomputer to simulate the dynamics numerically. We find that capture into resonance may result in chaotic motion. We discuss two mechanisms that can be invoked to disrupt high-order resonances: the "spontaneous" disruption of chaotic resonances and the disruption of resonances due to the tidal damping of a satellite's eccentricity while the satellite is in a nonsynchronous spin state. © 1988.
Proceedings Publications
- Castro, J., Malhotra, R., & Rosengren, A. (2023, oct). The possible origin of the Near-Earth Asteroid Kamo'oalewa (469219) as Lunar ejecta. In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
- Castro, J., Malhotra, R., & Rosengren, A. (2023, sep). The Dynamical Fate of Lunar Ejecta and the Possible Origin of Earth's Quasi-satellite Kamo'oalewa. In AAS/Division of Dynamical Astronomy Meeting, 55.
- Dietrich, J., Apai, D., Basant, R., & Malhotra, R. (2023, jan). An Integrated Analysis of Exoplanet Systems and Predicting Hidden Planets. In American Astronomical Society Meeting Abstracts, 55.
- Malhotra, R., & Ito, T. (2023, oct). The doubly resonant Plutinos. In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
- Markwardt, L., Lin, H., Gerdes, D., Malhotra, R., & Adams, F. (2023, jan). Characterizing Trojan Asteroid Populations Throughout the Solar System. In American Astronomical Society Meeting Abstracts, 55.
- Matheson, I., Malhotra, R., & Keane, J. (2023, oct). Orbital plane distribution of Plutinos. In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
- Spencer, D., Ragozzine, D., Volk, K., & Malhotra, R. (2023, sep). SBDynT: Characterizing the Solar System Small Bodies by Proper Elements and Chaos. In AAS/Division of Dynamical Astronomy Meeting, 55.
- Spencer, D., Volk, K., Ragozzine, D., & Malhotra, R. (2023, oct). SBDynT: Real-Time Characterization of Small Body Dynamics. In AAS/Division for Planetary Sciences Meeting Abstracts, 55.
- Castro, J., Malhotra, R., & Rosengren, A. (2022, may). Earth's Quasi-satellite Kamo'oalewa's Possible Origin as Lunar Ejecta. In AAS/Division of Dynamical Astronomy Meeting, 54.
- Castro-Cisneros, J. D., Malhotra, R., & Rosengren, A. J. (2022, jul). Earth's quasi-satellite Kamo'oalewa's possible origin as lunar ejecta. In 44th COSPAR Scientific Assembly. Held 16-24 July, 44.
- Dietrich, J., Apai, D., Basant, R., & Malhotra, R. (2022, dec). An Integrated Analysis of Multi-planet Systems and Predicting Hidden Planets. In AAS/Division for Planetary Sciences Meeting Abstracts, 54.
- Malhotra, R. (2022, jan). New results on orbital resonances. In Multi-Scale (Time and Mass) Dynamics of Space Objects, 364.
- Malhotra, R., & Ito, T. (2022, dec). Pluto near the edge of chaos. In AAS/Division for Planetary Sciences Meeting Abstracts, 54.
- Sharkey, B., Reddy, V., Malhotra, R., Thirouin, A., Kuhn, O., Conrad, A., Rothberg, B., Sanchez, J., Thompson, D., & Veillet, C. (2022, mar). Assessing the Origins of Earth Quasi-Satellite (469219) Kamo`oalewa. In 53rd Lunar and Planetary Science Conference, 2678.
- Castro-Cisneros, J., Malhotra, R., & Rosengren, A. (2021, jun). Near-Earth Asteroid Kamo`oalewa as Lunar Ejecta. In AAS/Division of Dynamical Astronomy Meeting, 53.
- Collaboration, V., Jones, R. L., Bannister, M. T., Bolin, B. T., Chandler, C. O., Chesley, S. R., Eggl, S., Greenstreet, S., Holt, T. R., Hsieh, H. H., Ivezic, Z., Juric, M., Kelley, M. S., Knight, M. M., Malhotra, R., Oldroyd, W. J., Sarid, G., Schwamb, M. E., Snodgrass, C., , Solontoi, M., et al. (2021, may). The Scientific Impact of the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) for Solar System Science. In Bulletin of the American Astronomical Society, 53.
- Malhotra, R., & Jain, J. (2021, jan). Predicting defects in object-oriented software using cost-sensitive classification. In Materials Science and Engineering Conference Series, 1022.
- Malhotra, R., Castro-Cisneros, J., Fitzgerald, J., Rosengren, A., Ross, S., Todorovic, N., & Wu, D. (2021, jun). What really goes on in the chaotic zones of the planets, from Earth to Neptune. In AAS/Division of Dynamical Astronomy Meeting, 53.
- Malhotra, R., Shakya, A., Ranjan, R., & Banshi, R. (2021, feb). Software defect prediction using Binary Particle Swarm Optimization with Binary Cross Entropy as the fitness function. In Journal of Physics Conference Series, 1767.
- Markwardt, L., Gowman, G., Gerdes, D., Malhotra, R., & Adams, F. (2021, mar). Latest Results from DECam Search for L5 Earth Trojans. In 52nd Lunar and Planetary Science Conference.
- Matheson, I., & Malhotra, R. (2021, jun). A measurement of the Kuiper Belt midplane from AI-classified objects. In AAS/Division of Dynamical Astronomy Meeting, 53.
- Pearce, L., & Malhotra, R. (2021, jun). An investigation of chaotic planetary dynamics induced by the wide stellar binary companion to Boyajian's Star. In AAS/Division of Dynamical Astronomy Meeting, 53.
- Volk, K., Malhotra, R., & Graham, S. (2021, jun). Mapping Neptune's resonances into the distant solar system. In AAS/Division of Dynamical Astronomy Meeting, 53.
- Volk, K., Malhotra, R., & Graham, S. (2021, oct). Mapping Neptune's resonances into the distant solar system. In AAS/Division for Planetary Sciences Meeting Abstracts, 53.
- Zaveri, N., & Malhotra, R. (2021, jun). Pluto's Resonant Orbit Visualized in 4D. In AAS/Division of Dynamical Astronomy Meeting, 53.
- Malhotra, R. (2020, aug). Asteroid belt dynamics and statistics. In AAS/Division of Dynamical Astronomy Meeting, 52.
- Malhotra, R., & Volk, K. (2020, oct). Corralling a distant unseen planet with orbital resonances \textemdash an update. In AAS/Division for Planetary Sciences Meeting Abstracts, 52.
- Markwardt, L., Gerdes, D., Malhotra, R., Becker, J., Hamilton, S., & Adams, F. (2020, jan). Searching for L5 Earth Trojans with DECam. In American Astronomical Society Meeting Abstracts \#235, 235.
- Markwardt, L., Gerdes, D., Malhotra, R., Becker, J., Hamilton, S., & Adams, F. (2020, mar). Searching for L5 Earth Trojans with DECam. In Lunar and Planetary Science Conference.
- Volk, K., & Malhotra, R. (2020, aug). Dynamical instabilities in systems of multiple short-period planets are likely driven by secular chaos: a case study of Kepler-102. In AAS/Division of Dynamical Astronomy Meeting, 52.
- Volk, K., & Malhotra, R. (2020, jan). Kepler-102: a case study for using dynamical constraints to characterize exoplanet systems. In American Astronomical Society Meeting Abstracts \#235, 235.
- Volk, K., & Malhotra, R. (2020, oct). Characterizing and predicting dynamical instabilities in multiplanet systems. In AAS/Division for Planetary Sciences Meeting Abstracts, 52.
- Amato, D., Rosengren, A. J., Malhotra, R., Sidorenko, V., & Ba{\`u}, G. (2019, Jun). The dynamical demise of Luna-3. In AAS/Division of Dynamical Astronomy Meeting, 51.
- JeongAhn, Y., Malhotra, R., & Reyes-Ruiz, M. (2019, Sep). Impact fluxes on 2014 MU69 and Pluto and their variations over secular timescales. In EPSC-DPS Joint Meeting 2019, 2019.
- Malhotra, R. (2019, Jun). Mean motion resonance widths at low and high eccentricity. In AAS/Division of Dynamical Astronomy Meeting, 51.
- Markwardt, L., Gerdes, D. W., Malhotra, R., Becker, J. C., Hamilton, S. J., & Adams, F. C. (2019, Sep). Search for L5 Earth Trojans with DECam. In EPSC-DPS Joint Meeting 2019, 2019.
- Reiland, N., Rosengren, A. J., Malhotra, R., & Bombardelli, C. (2019, Sep). Assessing and Minimizing Collisions in Satellite Mega-Constellations. In Proceedings of the Advanced Maui Optical and Space Surveillance Technologies Conference.
- Volk, K., & Malhotra, R. (2019, Jun). Not a simple relationship between Neptune's migration speed and Kuiper belt inclination excitation. In AAS/Division of Dynamical Astronomy Meeting, 51.
- Booth, M., Su, K., Macgregor, M., Wilner, D., Matr{\`a}, L., Flaherty, K., Hughes, M., Phillips, N., Malhotra, R., Hales, A., Morrison, S., Kral, Q., Ertel, S., Matthews, B., Dent, W., & Casassus, S. (2018, jul). Dust and Gas in the HD 95086 Planetary System. In Diversis Mundi: The Solar System in an Exoplanetary Context.
- Cambioni, S., Malhotra, R., Hergenrother, C., Rizk, B., Kidd, J., Drouet, d. C., Chesley, S., Shelly, F., Christensen, E., Farnocchia, D., & Lauretta, D. (2018, mar). An Upper Limit on Earth's Trojan Asteroid Population from OSIRIS-REx. In Lunar and Planetary Science Conference, 49.
- Lan, L., & Malhotra, R. (2018, apr). Neptune's 5:2 mean motion resonance in the Kuiper Belt. In AAS/Division of Dynamical Astronomy Meeting, 49.
- Malhotra, R. (2018, aug). Prospects for Unseen Planets Beyond Neptune. In Serendipities in the Solar System and Beyond, 513.
- Su}, K., MacGregor, M., Booth, M., Wilner, D., Malhotra, R., Morrison, S., & STDT, {. (2018, jan). ALMA 1.3 Millimeter Map of the HD 95086 System -- A Young Analog of the HR 8799 System. In American Astronomical Society Meeting Abstracts \#231, 231.
- Volk, K., & Malhotra, R. (2018, oct). A statistical exploration of the dynamical stability of Kepler and K2 multi-planet systems. In AAS/Division for Planetary Sciences Meeting Abstracts \#50, 50.
- Cambioni, S., & Malhotra, R. (2017, oct). "The Midplane of the Main Asteroid Belt and Its Warps". In AAS/Division for Planetary Sciences Meeting Abstracts, 49.
- Hergenrother, C., Malhotra, R., Rizk, B., Kidd, J., Drouet, d. C., Chesley, S., & Lauretta, D. (2017, mar). "A Search for Earth Trojan Asteroids with the OSIRIS-REx Spacecraft". In Lunar and Planetary Science Conference, 48.
- Malhotra, R. (2017, jun). "The Mass Function of Planets". In American Astronomical Society Meeting Abstracts, 230.
- Malhotra, R., & Volk, K. (2017, oct). "The Midplane of the Kuiper Belt and Its Unexpected Warps". In AAS/Division for Planetary Sciences Meeting Abstracts, 49.
- Reddy, V., Kuhn, O., Thirouin, A., Conrad, A., Malhotra, R., Sanchez, J., & Veillet, C. (2017, oct). "Ground-based Characterization of Earth Quasi Satellite (469219) 2016 HO3". In AAS/Division for Planetary Sciences Meeting Abstracts, 49.
- {JeongAhn}, Y., {Malhotra}, R., {Werner}, S., {Lee}, J., {Trang}, D., {Ip}, W., , M. (2016, oct). Spatial distribution of steep lunar craters may be linked to size-dependent orbital distribution of impactors. In AAS/Division for Planetary Sciences Meeting Abstracts, 48.
- {Malhotra}, R. (2016, may). The mass distribution function of planets in the Galaxy. In AAS/Division of Dynamical Astronomy Meeting, 47.
- {Malhotra}, R., , Y. (2016, mar). Mars/Moon Impact Rate Ratio of Kilometer-Size Impactors. In Lunar and Planetary Science Conference, 47.
- {Malhotra}, R., {Volk}, K., , X. (2016, oct). Corralling a distant unseen planet with extreme resonant Kuiper belt objects. In AAS/Division for Planetary Sciences Meeting Abstracts, 48.
- {Volk}, K., , R. (2016, oct). Evidence for a distant unseen solar system planet: Assessing the observational biases in the extreme Kuiper belt population. In AAS/Division for Planetary Sciences Meeting Abstracts, 48.
- {Volk}, K., {Malhotra}, R., , X. (2016, may). Dynamics of the Most Distant Kuiper Belt Objects. In AAS/Division of Dynamical Astronomy Meeting, 47.
- {Wang}, X., , R. (2016, may). High eccentricity MMRs in the circular planar restricted three-body problem. In AAS/Division of Dynamical Astronomy Meeting, 47.
- {Jones}, L., {Brown}, M., {Ivezi{'c}}, Z., {Juri{'c}}, M., {Malhotra}, R., , D. (2015, nov). "{Solar System science with the Large Synoptic Survey Telescope}". In AAS/Division for Planetary Sciences Meeting Abstracts, 47.
- {Malhotra}, R. (2015, mar). Oort Cloud Comet Encounters with Mars, Earth, Venus and Mercury. In Lunar and Planetary Science Conference, 46.
- {McEwen}, A., {Daubar}, I., {Ivanov}, B., {Oberst}, J., {Malhotra}, R., {JeongAhn}, Y., , S. (2015, mar). "{Current Impact Rate on Earth, Moon, and Mars}". In Lunar and Planetary Science Conference, 46.
Presentations
- Malhotra, R. (2018, April). Planet migration in the solar system. Joint Physics Astronomy Colloquium, Thomas Gold Lectures. Ithaca, NY.
- Malhotra, R. (2018, August). Prospects for unseen planets beyond Neptune. Planetary Science Colloquium. Tucson, AZ: Lunar and Planetary Laboratory.
- Malhotra, R. (2018, Jan). The Early History of our Solar System. Astrophysics Seminar. Bengaluru, India: Raman Research Institute.
- Malhotra, R. (2018, January). The early history of our solar system. Astrophysics seminar. Bengaluru, India: Raman Research Institute.
- Malhotra, R. (2018, June). Bombardment history of the planets. Workshop on Planetary Habitability. Austin, TX: University of Texas, Austin TX.
- Malhotra, R. (2018, June). Dynamics of Planetary Systems. Workshop on Planetary Habitability. Austin, TX: University of Texas, Austin TX.
- Malhotra, R. (2018, June). On the matter of habitability. Workshop on Habitability of Planets. Austin, TX: University of Texas - Austin TX.
- Malhotra, R. (2018, June). Resonant Kuiper Belt Objects - a review. Asia Oceania Geosciences Society Conference. Honolulu, HI: Asia Oceania Geosciences Society.More infoInvited "Distinguished Lecture"
- Malhotra, R. (2018, March). Planet migration in the Solar system: A new paradigm and its LPI origins. Lunar and Planetary Institute 50th Anniversary Science Symposium. Houston, TX: Lunar and Planetary Institute.
- Malhotra, R. (2018, March). Planet migration in the solar system: a new paradigm and its LPI origins. LPI 50th Anniversary Science Symposium. Houston, TX: Lunar and Planetary Institute.
- Malhotra, R. (2018, May). Prospects for unseen planets beyond Neptune. Astronomy Colloquium, Thomas Gold Lectures. Ithaca, NY: Cornell University.
- Malhotra, R. (2018, May). The mid-plane of the asteroid belt. Astronomy Seminar, Thomas Gold Lectures. Ithaca, NY: Cornell University.
- Malhotra, R. (2018, November). Prospects for unseen planets beyond Neptune. Physics Colloquium. Houston, TX: University of Houston.
- Malhotra, R. (2018, September). Prospects for unseen planets beyond Neptune. Lecar Prize Lecture and Colloquium. Harvard University, Cambridge, MA: Harvard-Smithsonian Center for Astrophysics.
- Malhotra, R. (2018, September). The mid-plane of the asteroid belt. Luncheon talk. Harvard University, Cambridge, MA: Harvard-Smithsonian Center for Astrophysics.
- Malhotra, R. (2017, April). A few points on the dynamical evolution of the young solar system. Colloquium. Victoria, British Columbia, Canada: Herzberg Institute for Astronomy.
- Malhotra, R. (2017, April). Corralling a distant unseen planet with extreme resonant Kuiper belt objects. Colloquium. Vancouver, British Columbia, Canada: University of British Columbia.
- Malhotra, R. (2017, April). \Earth Trojan Asteroid Survey with the OSIRIS-REx Spacecraft{Science motivations. OSIRIS-REx Science Team Meeting. Tucson, AZ: OSIRIS-REx Science Team.
- Malhotra, R. (2017, August). Prospects for Unseen Planets in the Distant Solar System,. Public talk. Fort Huachuca: Huachuca Astronomy Club,.
- Malhotra, R. (2017, February). The Structure and Evolution of the Solar System. Public talk. Saddlebrooke, AZ: Saddlebrooke SkyGazers Club.
- Malhotra, R. (2017, July). Prospects for Unseen Planets Beyond Neptune. Symposium: Serendipities in the Solar System and Beyond. Taiwan: National Central University.
- Malhotra, R. (2017, June). The mass function of planets. American Astronomical Society Meeting #230. Austin, TX: American Astronomical Society.
- Malhotra, R. (2017, March). A few points on the dynamical evolution of the young solar system. Planet Day. Toronto, Canada: Center for Planetary Science, University of Toronto.
- Malhotra, R. (2016, April). Planet Migration. Other Earths Dinner. Tucson, AZ: Earths in Other Solar Systems Project.
- Malhotra, R. (2016, December). orralling a distant unseen planet with extreme resonant Kuiper belt objects. Seminar. Tucson, AZ: National Optical Astronomical Observatories.
- Malhotra, R. (2016, January). Two studies in planetary dynamics: (i) Impact seasons on Mars, (ii) The mass function of planets in the Galaxy.. Colloquium. Gainesville, FL: University of Florida.
- Malhotra, R. (2016, July). The Solar System Beyond Neptune. Workshop on Solar System Puzzles. Taiwan: N.
- Malhotra, R. (2016, March). The Structure and Evolution of the Solar System. Public talk. Tucson, AZ: Osher Lifelong Learning Institute.
- Malhotra, R. (2016, May). Pluto Matters. Benjamin Dean lecture. San Francisco, CA: Morrison Planetarium.
- Malhotra, R. (2016, October). The Structure and Evolution of the Solar System. Public talk. Oro Valley, AZ: Sun City Astronomy Club.
- Malhotra, R. (2015, April). Space Science Research at the University of Arizona. USRA Regional Meeting, Region VIII. Boulder, CO: LASP -- University of Colorado.
- Malhotra, R. (2015, April). Two studies in planetary dynamics: (i) Impact seasons on Mars, (ii) The mass function of planets in the Galaxy.. Colloquium. Boulder, CO: Southwest Research Institute.
- Malhotra, R. (2015, August). The Galaxy is Teeming with Small Planets. Lunar and Planetary Laboratory Conference. Tucson, AZ: Lunar and Planetary Laboratory.
- Malhotra, R. (2015, July). Pluto and the Kuiper belt. Summer Science Saturday Lecture Series. Tucson, AZ: The University of Arizona.
- Malhotra, R. (2015, July). Pluto, the Kuiper belt and the early history of the solar system. Institute Seminar. Mountain View, CA: SETI Institute.
- Malhotra, R. (2015, March). A few points on the dynamical structure of planetary systems. Star and Planet Formation in the Southwest -- SPF1. Biosphere 2: The University of Arizona.
- Malhotra, R. (2015, March). Impact seasons on Mars. Seminar. Berkeley, CA: Center for Integrative Planetary Science -- University of California Berkeley.
- Malhotra, R. (2015, March). The mass distribution function of planets in the Galaxy. Seminar. Berkeley, CA: Berkeley Theoretical Astrophysics Center.
- Malhotra, R. (2015, November). Two studies in planetary dynamics: (i) Impact seasons on Mars, (ii) The mass function of planets in the Galaxy.. Colloquium. Los Angeles, CA: University of California Los Angeles.
- Malhotra, R. (2015, September). The mass function of planets in the Galaxy. Earths in Other Solar Systems -- All Hands Meeting. Tucson, AZ: Earths in Other Solar Systems Project.
- JeongAhn, Y., & Malhotra, R. (2014, nov). The current impactor flux on Mars and its seasonal variation. AAS/Division for Planetary Sciences Meeting Abstracts.
- Malhotra, R. (2014, April). Where do chaotic zone particles go. Bahcall Lunch. Princeton, NJ: Institute for Advanced Study.
- Malhotra, R. (2014, March). Tracking the Planets: Ours and Theirs. Girls Need Their Space. Tucson, AZ: The University of Arizona.
- Malhotra, R. (2014, may). A few points on the dynamical evolution of the young solar system. AAS/Division of Dynamical Astronomy Meeting.
- Morrison, S. J., & Malhotra, R. (2014, may). Planetary chaotic zone clearing: destinations and timescales. AAS/Division of Dynamical Astronomy Meeting.
- Morrison, S. J., Malhotra, R., & Su, K. Y. (2014, nov). The Planetary System of HD 95086-A Young Analog of HR 8799?. AAS/Division for Planetary Sciences Meeting Abstracts.
- Su, K. Y., Morrison, S. J., Malhotra, R., Balog, Z., & Smith, P. S. (2014, nov). The Debris Structures of HD 95086 - A Young Analog of HR 8799. AAS/Division for Planetary Sciences Meeting Abstracts.
- JeongAhn, Y., & Malhotra, R. (2013, Fall). The non-uniform distribution of the perihelia of near-Earth objects. DPS meeting #45American Astronomical Society.More info#106.01
- Malhotra, R. (2013, April). Canadian Insititute for Theoretical Astrophysics. Canadian Insititute for Theoretical Astrophysics.
- Malhotra, R. (2013, April). The early history of our solar system. Colloquium. Toronto, Canada: University of Toronto.
- Malhotra, R. (2013, October). The early history of our solar system. Colloquim. Fort Collins, CO: Colorado State University.
- Malhotra, R., Petrovich, C., & Tremaine, S. (2013, Fall). In-situ Planet Formation: Implications for Planets near Resonances. DPS meeting #45American Astronomical Society.More info#300.05
- Petrovich, C., Malhotra, R., & Tremaine, S. (2013, Fall). In-situ Panet Formation: Implications for the orbital distribution around resonances, Exoplanets in Muti-body Systems in the Kepler Era. Conference at the Aspen Center for Physics.
- Belbruno, E., Moro-Martin, A., Malhotra, R., & Savransky, D. (2012, Fall). Chaotic exchange of solid material between planetary systems: implications for lithopanspermia. European Planetary Science Congress EPSC2012-139.
- JeongAhn, Y., & Malhotra, R. (2012, Fall). On the Distribution of Angular Orbital Elements of Near-earth Objects. American Astronomical Society, AAS Meeting #220.More info#128.01
- Malhotra, R. (2012, April). Lecture series on Solar System Dynamics. UNAM. Ensenada, Mexico.
- Malhotra, R. (2012, July). The dynamical history of our solar system. 39th COSPAR Scientific Assembly. Mysore, India: COSPAR.
- Malhotra, R. (2011, March). The solar system in time. Women in Science and Technology. New Delhi, India: Indian Institute of Technology -- Delhi.
Poster Presentations
- Jones, R. L., Ivezic, Z., Malhotra, R., Becker, A. C., Fernandez, Y., Myers, J., Solontoi, M., & Parker, A. H. (2014, nov). Solar System Science with LSST. AAS/Division for Planetary Sciences Meeting Abstracts.
- Volk, K., & Malhotra, R. (2014, Fall). Ordering Mean Motion Resonances with the Farey Tree: Application to the Kuiper Belt. DPS meeting #45American Astronomical Society.More info#414.01
- Malhotra, R. (2012, July). The dynamical history of our solar system. 39th COSPAR Scientific Assembly. Mysore, India.
- Volk, K., & Malhotra, R. (2012, Fall). The Origin of Resonant Kuiper Belt Objects. DDA meeting #43American Astronomical Society.More info#5.02
- Volk, K., & Malhotra, R. (2012, Fall). The Origin of Resonant Kuiper Belt Objects. DPS meeting #44American Astronomical Society.More info#405.06
Creative Productions
- Malhotra, R. (2017. The Search for Planet 9. TEDx Portland. Portland, OR: TEDx Portland.
- Malhotra, R. (2013. Fractions for Planets. The Art of Planetary Science. Tucson, AZ: University of Arizona.
Others
- Markwardt, L., Adams, F., Gerdes, D., Lin, H. W., Malhotra, R., & Napier, K. (2021). The First Near-IR Spectroscopic Survey of Neptune Trojans.
- Agol, E., Carey, S., Delrez, L., Demory, B., Fabrycky, D., Gillon, M., Grimm, S., Ingalls, J., Malhotra, R., Morris, B., Raymond, S., Triaud, A., Bolmont, E., & Burgasser, A. (2019). Revisiting and refining the model of TRAPPIST-1 with Spitzer.