J. Serena Kim

Interests

Research

Star and planet formation, circumstellar disk evolution, feedback from massive stars to next generation star and planet formation, astrobiology, Stellar birth environment and protoplanetary disk evolution.

Teaching

Life in the Universe, Astrobiology, Stars, Astronomy General Education

Courses

Scholarly Contributions

Journals/Publications

• Kreckel, K., Egorov, O., Egorova, E., Blanc, G., Drory, N., Kounkel, M., Stringfellow, G., Stutz, A., Zari, E., Barrera-Ballesteros, J., Bizyaev, D., Brownstein, J., Congiu, E., Hillenbrand, L., Ibarra-Medel, H., Jin, Y., Johnston, E., Jones, A., Kim, J., , Kollmeier, J., et al. (2024). SDSS-V Local Volume Mapper (LVM): A glimpse into Orion. Astronomy and Astrophysics, 689. doi:10.1051/0004-6361/202449943
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  Context. The Orion Molecular Cloud complex, one of the nearest (D = 406 pc) and most extensively studied massive star-forming regions, is ideal for constraining the physics of stellar feedback, but its ∼12 deg diameter on the sky requires a dedicated approach to mapping ionized gas structures within and around the nebula. Aims. The Sloan Digital Sky Survey (SDSS-V) Local Volume Mapper (LVM) is a new optical integral field unit (IFU) that will map the ionized gas within the Milky Way and Local Group galaxies, covering 4300 deg2 of the sky with the new LVM Instrument (LMV-I). Methods. We showcase optical emission line maps from LVM covering 12 deg2 inside of the Orion belt region, with 195 000 individual spectra combined to produce images at 0.07 pc (35.3″) resolution. This is the largest IFU map made (to date) of the Milky Way, and contains well-known nebulae (the Horsehead Nebula, Flame Nebula, IC 434, and IC 432), as well as ionized interfaces with the neighboring dense Orion B molecular cloud. Results. We resolve the ionization structure of each nebula, and map the increase in both the [S II]/Hα and [N II]/Hα line ratios at the outskirts of nebulae and along the ionization front with Orion B. [O III] line emission is only spatially resolved within the center of the Flame Nebula and IC 434, and our ∼0.1 pc scale line ratio diagrams show how variations in these diagnostics are lost as we move from the resolved to the integrated view of each nebula. We detect ionized gas emission associated with the dusty bow wave driven ahead of the star σ Orionis, where the stellar wind interacts with the ambient interstellar medium. The Horsehead Nebula is seen as a dark occlusion of the bright surrounding photo-disassociation region. This small glimpse into Orion only hints at the rich science that will be enabled by the LVM.
• Saad, S., Lane, K., Kounkel, M., Stassun, K., Kim, J., Stringfellow, G., Wolk, S., Hillenbrand, L., Hernández, J., López-Valdivia, R., Peña Ramírez, K., & Román-Zúñiga, C. (2024). ABYSS. II. Identification of Young Stars in Optical SDSS Spectra and Their Properties. Astronomical Journal, 167(3). doi:10.3847/1538-3881/ad2001
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  We developed a tool that measures equivalent widths of various lines in low-resolution optical spectra, and it was applied to stellar spectra obtained as part of SDSS-V and LAMOST programs. These lines, such as Li i, which directly indicates stellar youth, or optical H i and Ca ii, which in emission indicate activity associated with stellar youth, are commonly seen in YSOs. We observe several notable differences in the properties of these lines between YSOs and the field stars. Using these data, we devise a set of criteria through which it is possible to confirm the youth of stars that have been observed by the ABYSS program, as well as to identify likely young stars that have serendipitously been observed by other programs. We examine the decrement of H lines seen in emission in CTTSs, and estimate the properties of the accretion stream that is responsible for the production of these lines. Finally, we examine the evolution of Li i as a function of age, and characterize the scatter in its abundance that appears to be intrinsic in young M dwarfs.
• Sicilia-Aguilar, A., Kahar, R., Roccatagliata, V., Froebrich, D., Galindo-Guil, F., Campbell-White, J., Kim, J., Schlueter, L., Teixeira, P., Matsumura, S., Fang, M., Scholz, A., Frasca, A., Garufi, A., Herbert, C., Manara, C., Mendigutía, I., Pelayo-Baldárrago, M., & Ábrahám, P. (2024). North-PHASE: Studying periodicity, hot spots, accretion stability, and early evolution in young stars in the Northern hemisphere. Monthly Notices of the Royal Astronomical Society, 532(2), 2108. doi:10.1093/mnras/stae1588
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  We present the overview and first results from the North-PHASE Legacy Survey, which follows six young clusters for five years, using the 2 deg FoV of the JAST80 telescope from the Javalambre Observatory (Spain). North-PHASE investigates stellar variability on time-scales from days to years for thousands of young stars distributed over entire clusters. This allows us to find new YSO, characterize accretion, and study inner disc evolution within the cluster context. Each region (Tr 37, Cep OB3, IC 5070, IC 348, NGC 2264, and NGC 1333) is observed in six filters (SDSS griz, u band, and J0660, which covers H), detecting cluster members as well as field variable stars. Tr 37 is used to prove feasibility and optimize the variability analysis techniques. In Tr 37, variability reveals 50 new YSO, most of them proper motion outliers. North-PHASE independently confirms the youth of astrometric members, efficiently distinguishes accreting and non-accreting stars, reveals the extent of the cluster populations along Tr37/IC 1396 bright rims, and detects variability resulting from rotation, dips, and irregular bursts. The proper motion outliers unveil a more complex star formation history than inferred from Gaia alone, and variability highlights previously hidden proper motion deviations in the surrounding clouds. We also find that non-YSO variables identified by North-PHASE cover a different variability parameter space and include long-period variables, eclipsing binaries, RR Lyr, and Scuti stars. These early results also emphasize the power of variability to complete the picture of star formation where it is missed by astrometry.
• Ballering, N., Cleeves, L., Haworth, T., Bally, J., Eisner, J., Ginsburg, A., Boyden, R., Fang, M., & Kim, J. (2023). Isolating Dust and Free-Free Emission in ONC Proplyds with ALMA Band 3 Observations. Astrophysical Journal, 954(2), 127. doi:10.3847/1538-4357/ace901
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  The Orion Nebula Cluster (ONC) hosts protoplanetary disks experiencing external photoevaporation by the cluster’s intense UV field. These “proplyds” are comprised of a disk surrounded by an ionization front. We present ALMA Band 3 (3.1 mm) continuum observations of 12 proplyds. Thermal emission from the dust disks and free-free emission from the ionization fronts are both detected, and the high-resolution (0.″057) of the observations allows us to spatially isolate these two components. The morphology is unique compared to images at shorter (sub)millimeter wavelengths, which only detect the disks, and images at longer centimeter wavelengths, which only detect the ionization fronts. The disks are small (r d = 6.4-38 au), likely due to truncation by ongoing photoevaporation. They have low spectral indices (α ≲ 2.1) measured between Bands 7 and 3, suggesting the dust emission is optically thick. They harbor tens of Earth masses of dust as computed from the millimeter flux using the standard method although their true masses may be larger due to the high optical depth. We derive their photoevaporative mass-loss rates in two ways: first, by invoking ionization equilibrium and second, by using the brightness of the free-free emission to compute the density of the outflow. We find decent agreement between these measurements and M ̇ = 0.6-18.4 × 10−7 M ⊙ yr−1. The photoevaporation timescales are generally shorter than the ∼1 Myr age of the ONC, underscoring the known “proplyd lifetime problem.” Disk masses that are underestimated due to being optically thick remains one explanation to ease this discrepancy.
• Campbell, H., Khilfeh, E., Covey, K., Kounkel, M., Ballantyne, R., Corey, S., Roman-Lopes, A., Stassun, K., Stringfellow, G., Borissova, J., Chojnowski, S., Kim, J., Serna, J., Stutz, A., Ybarra, J., Fernández-Trincado, J., Hernández, J., Longa-Peña, P., López-Valdivia, R., , Martínez, E., et al. (2023). Pre-main-sequence Brackett Emitters in the APOGEE DR17 Catalog: Line Strengths and Physical Properties of Accretion Columns. Astrophysical Journal, 942(1). doi:10.3847/1538-4357/aca324
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  Very young (t ≲ 10 Myr) stars possess strong magnetic fields that channel ionized gas from the interiors of their circumstellar disks to the surface of the star. Upon impacting the stellar surface, the shocked gas recombines and emits hydrogen spectral lines. To characterize the density and temperature of the gas within these accretion streams, we measure equivalent widths of Brackett (Br) 11-20 emission lines detected in 1101 APOGEE spectra of 326 likely pre-main-sequence accretors. For sources with multiple observations, we measure median epoch-to-epoch line strength variations of 10% in Br11 and 20% in Br20. We also fit the measured line ratios to predictions of radiative transfer models by Kwan & Fischer. We find characteristic best-fit electron densities of n e = 1011-1012 cm−3, and excitation temperatures that are inversely correlated with electron density (from T ∼ 5000 K for n e ∼ 1012 cm−3 to T ∼ 12,500 K at n e ∼ 1011 cm−3). These physical parameters are in good agreement with predictions from modeling of accretion streams that account for the hydrodynamics and radiative transfer within the accretion stream. We also present a supplementary catalog of line measurements from 9733 spectra of 4255 Brackett emission-line sources in the APOGEE Data Release 17 data set.
• Haworth, T. J., Reiter, M., O’Dell, C. R., Zeidler, P., Berne, O., Manara, C. F., Ballabio, G., Kim, J. S., Bally, J., Goicoechea, J. R., Aru, M., Gupta, A., & Miotello, A. (2023). The VLT MUSE NFM view of outflows and externally photoevaporating discs near the orion bar★. Monthly Notices of the Royal Astronomical Society, 525(3), 4129-4142. doi:10.1093/mnras/stad2581
• Haworth, T., Reiter, M., O'Dell, C., Zeidler, P., Berne, O., Manara, C., Ballabio, G., Kim, J., Bally, J., Goicoechea, J., Aru, M., Gupta, A., & Miotello, A. (2023). The VLT MUSE NFM view of outflows and externally photoevaporating discs near the orion bar∗. Monthly Notices of the Royal Astronomical Society, 525(3). doi:10.1093/mnras/stad2581
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  We present Very Large Telescope/Multi-Unit Spectroscopic Explorer Narrow Field Mode observations of a pair of disc-bearing young stellar objects towards the Orion Bar: 203-504 and 203-506. Both of these discs are subject to external photoevaporation, where winds are launched from their outer regions due to environmental irradiation. Intriguingly, despite having projected separation from one another of only 1.65 arcsec(660 au at 400 pc), 203-504 has a classic teardrop shaped 'proplyd' morphology pointing towards θ2 Ori A (indicating irradiation by the EUV of that star, rather than Ori C) but 203-506 has no ionization front, indicating it is not irradiated by stellar EUV at all. However, 203-506 does show [C i] 8727 Å and [O i] 6300 Å in emission, indicating irradiation by stellar FUV. This explicitly demonstrates the importance of FUV irradiation in driving mass loss from discs. We conclude that shielding of 203-506 from EUV is most likely due to its position on the observers side of an ionized layer lying in the foreground of the Huygens Region. We demonstrate that the outflow HH 519, previously thought to be emanating from 203-504 is actually an irradiated cloud edge and identify a new compact outflow from that object approximately along our line of sight with a velocity ∼130 km s-1.
• Kounkel, M., Covey, K., Stutz, A., Roman-Lopes, A., Campbell, H., Khilfeh, E., Tapia, M., Stringfellow, G., Downes, J., Stassun, K., Minniti, D., Bayo, A., Kim, J., Ybarra, J., Serna, J., Lane, R., Beaton, R., Bizyaev, D., Pan, K., , Fernández-Trincado, J., et al. (2023). Stellar Properties for a Comprehensive Collection of Star-forming Regions in the SDSS APOGEE-2 Survey* Based on SDSS Data Releases 16 and 17.. Astronomical Journal, 165(2). doi:10.3847/1538-3881/aca3a4
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  The Sloan Digital Sky Survey IV APOGEE-2 primary science goal was to observe red giant stars throughout the Galaxy to study its dynamics, morphology, and chemical evolution. The APOGEE instrument, a high-resolution 300-fiber H-band (1.55-1.71 μm) spectrograph, is also ideal to study other stellar populations in the Galaxy, among which are a number of star-forming regions and young open clusters. We present the results of the determination of six stellar properties (T eff, log g , [Fe/H], L/L ⊙, M/M ⊙, and age) for a sample that is composed of 3360 young stars, of subsolar to supersolar types, in 16 Galactic star formation and young open cluster regions. Those sources were selected by using a clustering method that removes most of the field contamination. Samples were also refined by removing targets affected by various systematic effects of the parameter determination. The final samples are presented in a comprehensive catalog that includes all six estimated parameters. This overview study also includes parameter spatial distribution maps for all regions and Hertzsprung-Russell ( log L / L ⊙ vs. T eff) diagrams. This study serves as a guide for detailed studies on individual regions and paves the way for the future studies on the global properties of stars in the pre-main-sequence phase of stellar evolution using more robust samples.
• Kounkel, M., Zari, E., Covey, K., Tkachenko, A., Stassun, K., Stutz, A., Stringfellow, G., Roman-Lopes, A., Bayo, A., Kim, J., Cao, L., Wolk, S., Kollmeier, J., Rojas-Ayala, B., Hernández, J., López-Valdivia, R., Ramírez, K., & Zúñiga, C. (2023). ABYSS. I. Targeting Strategy for the APOGEE and BOSS Young Star Survey in SDSS-V. Astrophysical Journal, Supplement Series, 266(1). doi:10.3847/1538-4365/acc106
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  The fifth iteration of the Sloan Digital Sky Survey is set to obtain optical and near-infrared spectra of ∼5 million stars of all ages and masses throughout the Milky Way. As a part of these efforts, APOGEE and BOSS Young Star Survey (ABYSS) will observe ∼105 stars with ages
• Sicilia-Aguilar, A., Fang, M., Roccatagliata, V., Kim, J., García-Álvarez, D., & Pelayo-Baldárrago, M. (2023). Star formation in IC1396: Kinematics and subcluster structure revealed by Gaia. Astronomy and Astrophysics, 669. doi:10.1051/0004-6361/202244265
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  Aims. We investigate the star formation history of the IC1396 region by studying its kinematics and completing the population census. Methods. We used multiwavelength data, combining optical spectroscopy to identify and classify new members and near-infrared photometry to trace shocks, jets, and outflows as well as the interactions between the cluster members and the cloud. We also used Gaia EDR3 data to identify new potential members in the multidimensional proper motion and parallax space. Results. The revised Gaia EDR3 distance is 925±73 pc, slightly closer than previously obtained with DR2. The Gaia data reveal four distinct subclusters in the region. These subclusters are consistent in distance but display differences in proper motion. This result, with their age differences, hints toward a complex and varied star formation history. The Gaia data also unveil intermediate-mass objects that tend to evade spectroscopic and disk surveys. Our analysis has allowed us to identify 334 new members. We estimate an average age of ~4 Myr, confirming previous age estimates. With the new members added to our study, we estimate a disk fraction of 28%, lower than previous values, due to our method detecting mainly new, diskless, intermediate-mass stars. We find age differences between the subclusters, which offers evidence of a complex star formation history with different episodes of star formation.
• Bialy, S., Bryden, G., Burkhart, B., Chung, H., Godard, B., Hamden, E. T., Hasegawa, Y., Haworth, T. J., Hoadley, K., Hoenk, M., Imara, N., Kennicutt, R., Kiessling, A., Kim, D., Kong, S., Krumholz, M., Lee, M., Luthman, E., McGuire, J. P., , Nikzad, S., et al. (2022).

  Hyperion: the origin of the stars. A far UV space telescope for high-resolution spectroscopy over wide fields

  . Journal of Astronomical Telescopes, Instruments, and Systems, 8(04). doi:10.1117/1.jatis.8.4.044008
• Hasegawa, Y., Haworth, T. J., Hoadley, K., Kim, J. S., Goto, H., Juzikenaite, A., Turner, N. J., Pascucci, I., & Hamden, E. T. (2022). "Determining Dispersal Mechanisms of Protoplanetary Disks Using Accretion and Wind Mass Loss Rates". apjl, 926(2), L23.
• Haworth, T. J., Kim, J. S., Qiao, L., Winter, A. J., Williams, J. P., Clarke, C. J., Owen, J. E., Facchini, S., Ansdell, M., Kama, M., & Ballabio, G. (2022). "An APEX search for carbon emission from NGC 1977 proplyds". mnras, 512(2), 2594-2603.
• Sprague, D., Culhane, C., Kounkel, M., Olney, R., Covey, K., Hutchinson, B., Lingg, R., Stassun, K. G., Rom{\'an-Z\'u\~niga}, C. G., Roman-Lopes, A., Nidever, D., Beaton, R. L., Borissova, J., Stutz, A., Stringfellow, G. S., Ram{\'\irez}, K. P., Ram{\'\irez-Preciado}, V., Hern{\'andez}, J., Kim, J. S., & Lane, R. R. (2022). APOGEE Net: An Expanded Spectral Model of Both Low-mass and High-mass Stars. \aj, 163(4), 152.
• Fang, M., Kim, J. S., Pascucci, I., & Apai, D. (2021). An Improved Hertzsprung-Russell Diagram for the Orion Trapezium Cluster. Astrophysical Journal, 908(1), 49.
• Haworth, T. J., Kim, J. S., Winter, A. J., Hines, D. C., Clarke, C. J., Sellek, A. D., Ballabio, G., & Stapelfeldt, K. R. (2021). Proplyds in the flame nebula NGC 2024. Monthly Notices of the Royal Astronomical Society, 501(3), 3502-3514.
• Kim, S., Lim, B., Bessell, M. S., Kim, J. S., & Sung, H. (2021). The Sejong Open Cluster Survey (SOS). VII. A Photometric Study of the Young Open Cluster IC 1590. Astronomical Journal, 162(4), 140.
• Silverberg, S. M., G{"unther}, H. M., Kim, J. S., Principe, D. A., & Wolk, S. J. (2021). What's Behind the Elephant's Trunk? Identifying Young Stellar Objects on the Outskirts of IC 1396. Astronomical Journal, 162(6), 279.
• Ballabio, G., Clarke, C. J., Haworth, T. J., Hines, D. C., Kim, J. S., Sellek, A. D., Stapelfeldt, K. R., & Winter, A. J. (2020).

  Proplyds in the flame nebula NGC 2024

  . Monthly Notices of the Royal Astronomical Society, 501(3), 3502-3514. doi:10.1093/mnras/staa3918
• Fang, M., Hillenbrand, L. A., Kim, J. S., Findeisen, K., Herczeg, G. J., Carpenter, J. M., Rebull, L. M., & Wang, H. (2020). The First Extensive Spectroscopic Study of Young Stars in the North America and Pelican Nebulae. Astrophysical Journal, 904(2), 146.
• Lim, B., Hong, J., Yun, H., Hwang, N., Kim, J. S., Lee, J., Park, B., & Park, S. (2020). The Origin of a Distributed Stellar Population in the Star-forming Region W4. Astrophysical Journal, 899(2), 121.
• Ram{\'\irez-Preciado}, V. G., Roman-Lopes, A., Rom{\'an-Z\'u\~niga}, C. G., Hern{\'andez}, J., Garc{\'\ia-Hern\'andez}, D., Stassun, K., Stringfellow, G. S., & Kim, J. S. (2020). Spectral Classification of B Stars: The Empirical Sequence Using SDSS-IV/APOGEE Near-IR Data. Astrophysical Journal, 894(1), 5.
• 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, Astro 2020 Science White Paper, 51(3), 475.
• Drake, J., Alvarado-G{'omez}, J., Airapetian, V., Cauley, P., Argiroffi, C., Browning, M., Christian, D., Cohen, O., Corrales, L., Danchi, W., Val-Borro, M. .., Dong, C., Forman, W., France, K., Gallo, E., Garcia-Sage, K. .., Garraffo, C., Gelino, D., Gronoff, G., , G{"unther}, H., et al. (2019). High-Energy Photon and Particle Effects on Exoplanet Atmospheres and Habitability. ASTRO2020 White Paper, https://arxiv.org/pdf/1903.12338v1.pdf.
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  Astro2020 Science White Paper
• Fang, M., Pascucci, I., Kim, J. S., & Edwards, S. (2019). Double-peaked [O i] Profile: A Likely Signature of the Gaseous Ring around KH 15D. The Astrophysical Journal, 879(1), L10.
• Gaspar, A., Apai, D., Augereau, J., Ballering, N. P., Beichman, C. A., Boccaletti, A., Booth, M., Bowler, B. P., Bryden, G., Chen, C. H., Currie, T., Danchi, W. C., Debes, J., Defr{\`ere}, D., Ertel, S., Jackson, A. P., Kalas, P. G., Kennedy, G. M., Kenworthy, M. A., , Kim, J. S., et al. (2019). Modeling Debris Disk Evolution. \baas, 51(3), 69.
• Harman, C., Airapetian, V., Apai, D., Arney, G., Buzasi, D., Cadillo-Quiroz, H., Danchi, B., Domagal-Goldman, S., Dong, C., Dressing, C., Felton, R., Fisher, T. M., France, K., Gelino, D., Hartnett, H. E., Kalas, P., Kane, S. R., Kiang, N. Y., Kim, J. S., , Kopparapu, R., et al. (2019). A Balancing Act: Biosignature and Anti-Biosignature Studies in the Next Decade and Beyond. Astro 2020 Science White Paper, 51(3), 414.
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  https://113qx216in8z1kdeyi404hgf-wpengine.netdna-ssl.com/wp-content/uploads/2019/05/414_harman.pdf
• Isella, A., Ricci, L., Andrews, S., Baruteau, C., Berger, J., Bergin, E., Birnstiel, T., Bowler, B., Brogan, C., Carrasco, G. C., Chandler, C., Currie, T., Cuzzi, J., D'Angelo, G., Dong, R., Duchene, G., Dutrey, A., Ercolano, B., Espaillat, C., , Estrada, P., et al. (2019). Observing Planetary Systems in the Making. \baas, 51(3), 174.
• Jang-Condell, H. .., Brittain, S., Weinberger, A., Liu, M., Faherty, J., Bae, J., Andrews, S., Ansdell, M., Birnstiel, T., Boss, A., Close, L., Currie, T., Desch, S., Dodson-Robinson, S. .., Dong, C., Duchene, G., Espaillat, C., Follette, K., Gaidos, E., , Gao, P., et al. (2019). Protoplanetary Disk Science Enabled by Extremely Large Telescopes. arXiv e-prints.
• Kounkel, M., Covey, K., Moe, M., Kratter, K., Su{'arez}, G., Stassun, K., Rom{'an-Z'u~niga}, C., Hernandez, J., Kim, J., Pe{~na, R. K., Roman-Lopes, A. .., Stringfellow, G., Jaehnig, K., Borissova, J., Tofflemire, B., Krolikowski, D., Rizzuto, A., Kraus, A., Badenes, C., , Longa-Pe{~na}, P., et al. (2019). Close companions around young stars. The Astrophysical Journal, 157, 196. doi:https://doi.org/10.3847/1538-3881/ab13b1
• Lyra, W., Haworth, T., Bitsch, B., Casassus, S., Cuello, N., Currie, T., G{'asp'ar}, A., Jang-Condell, H. .., Klahr, H., Leigh, N., Lodato, G., Mac, L. M., Maddison, S., Mamatsashvili, G., McNally, C., Isella, A., P{'erez}, S., Ricci, L., Sengupta, D., , Stamatellos, D., et al. (2019). Planet formation: The case for large efforts on the computational side. arXiv e-prints.
• Meng, H., Rieke, G. H., Kim, J. S., Sicilia-Aguilar, A., Cross, N., Esplin, T., Rebull, L. M., & Hodapp, K. W. (2019). Near-infrared Variability of Low-mass Stars in IC 1396A and Tr 37. The Astrophysical Journal, 878(1), 7.
• Roman-Lopes, A. .., Rom{'an-Z'u~niga}, C., Tapia, M., Hern{'andez}, J., Ram{'{i}rez-Preciado}, V., Stringfellow, G., Ybarra, J., Kim, J., Minniti, D., Covey, K., Kounkel, M., Su{'arez}, G., Borissova, J., Garc{'{i}a-Hern'andez}, D., Zamora, O., & Trujillo, J. (2019). Massive Stars in the SDSS-IV/APOGEE-2 Survey. II. OB-stars in the W345 Complexes. The Astrophysical Journal, 873, 66. doi:10.3847/1538-4357/ab0305
• Cottle, J., Covey, K., Su{'arez}, G., Rom{'an-Z'u~niga}, C., Schlafly, E., Downes, J., Ybarra, J., Hernandez, J., Stassun, K., Stringfellow, G., Getman, K., Feigelson, E., Borissova, J., Kim, J., Roman-Lopes, A. .., Da Rio, N., De Lee, N., Frinchaboy, P., Kounkel, M., , Majewski, S., et al. (2018). The APOGEE-2 Survey of the Orion Star-forming Complex. I. Target Selection and Validation with Early Observations. Astrophysical Journal Supplement, 236, 27.
• Eisner, J., Arce, H., Ballering, N., Bally, J., Andrews, S., Boyden, R., Di Francesco, J., Fang, M., Johnstone, D., Kim, J., Mann, R., Matthews, B., Pascucci, I., Ricci, L., Sheehan, P., & Williams, J. (2018). Protoplanetary Disk Properties in the Orion Nebula Cluster: Initial Results from Deep, High-resolution ALMA Observations. Astrophysical Journal, 860, 77. doi:10.3847/1538-4357/aac3e2
• Fang, M., Kim, J., Pascucci, I., Apai, D., Zhang, L., Sicilia-Aguilar, A. .., Alonso-Martinez, M. .., Eiroa, C., & Wang, H. (2018). VizieR Online Data Catalog: Spectroscopy of the foreground population in Orion A (Fang+, 2017). VizieR Online Data Catalog, 515.
• Jose, J., Pandey, A., Samal, M., Ojha, D., Ogura, K., Kim, J., Kobayashi, N., Goyal, A., Chauhan, N., & Eswaraiah, C. (2018). VizieR Online Data Catalog: YSOs on HII complex Sh2-252 (Jose+, 2013). VizieR Online Data Catalog, 743.
• Kounkel, M., Covey, K., Su{'arez}, G., Rom{'an-Z'u~niga}, C., Hernandez, J., Stassun, K., Jaehnig, K., Feigelson, E., Pe{~na, R. K., Roman-Lopes, A. .., Da Rio, N., Stringfellow, G., Kim, J., Borissova, J., Fern{'andez-Trincado}, J., Burgasser, A., Garc{'{i}a-Hern'andez}, D., Zamora, O., Pan, K., & Nitschelm, C. (2018). The APOGEE-2 Survey of the Orion Star-forming Complex. II. Six-dimensional Structure. Astrophysical Journal, 156, 84. doi:10.3847/1538-4365/aabada
• Wu, Y., Close, L., Kim, J., Males, J., & Morzinski, K. (2018). The Intricate Structure of HH 508, the Brightest Microjet in the Orion Nebula. Astrophysical Journal Letters, 854, 144. doi:https://doi.org/10.3847/1538-4357/aaa96b
• Da Rio, N., Tan, J., Covey, K., Cottaar, M., Foster, J., Cullen, N., Tobin, J., Kim, J., Meyer, M., Nidever, D., Stassun, K., Chojnowski, S., Flaherty, K., Majewski, S., Skrutskie, M., Zasowski, G., & Pan, K. (2017). IN-SYNC. V. Stellar Kinematics and Dynamics in the Orion A Molecular Cloud. Astrophysical Journal, 845, 105.
• Fang, M., Kim, J., Pascucci, I., Apai, D., Zhang, L., Sicilia-Aguilar, A. .., Alonso-Mart{\'{\i}nez}, M., Eiroa, C., & Wang, H. (2017). NGC 1980 Is Not a Foreground Population of Orion: Spectroscopic Survey of Young Stars with Low Extinction in Orion A. Astrophysical Journal, 153, 188.
• Kim, J. S. (2016). IN-SYNC. IV. The Young Stellar Population in the Orion A Molecular Cloud. The Astrophysical Journal, 818, 16. doi:10.3847/0004-637X/818/1/59
• Kim, J. S. (2016). STAR FORMATION IN W3-AFGL333: YOUNG STELLAR CONTENT, PROPERTIES AND ROLES OF EXTERNAL FEEDBACK. Astrophysical Journal.
• Kim, J. S., Clarke, C. J., Fang, M., & Facchini, S. (2016). Proplyds Around a B1 Star: 42 Orionis in NGC 1977. Astrophysical Journal Letters, 826, 15. doi:10.3847/2041-8205/826/1/L15
• Kim, J. S., Fang, M., Pascucci, I., Apai, D., & Manara, C. F. (2016). A Candidate Planetary-mass Object with a Photoevaporating Disk in Orion. Astrophysical Journal Letters, 833, 16. doi:10.3847/2041-8213/833/2/L16
• Kim, J. S., Lim, B., Sung, H., Bessell, M. S., Hwang, N., & Park, B. (2016). A Constraint on the Formation Timescale of the Young Open Cluster NGC 2264: Lithium Abundance of Pre-main Sequence Stars. Astrophysical Journal, 831, 116. doi:10.3847/0004-637X/831/2/116
• Shvonski, A., Mamajek, E., Kim, J., Meyer, M., & Pecaut, M. (2016). A Spitzer Space Telescope Survey for Dusty Debris Disks in the Nearby 32 Orionis Group. ArXiv e-prints.
• Kim, J. S. (2015). An Optical Spectroscopic Survey of the Serpens Main Cluster: Evidence for Two Populations?. Astronomical Journal, 149, 16. doi:10.1088/0004-6256/149/3/103
• Kim, J. S. (2015). Sejong Open Cluster Survey (SOS) - IV. The Young Open Clusters NGC 1624 and NGC 1931. Astronomical Journal. doi:10.1088/0004-6256/149/4/127
• Kim, J. S. (2015). Sejong Open Cluster Survey (SOS) - V. The Active Star Forming Region SH 2-255-257. Journal of the Korean Astronomical Society,, 48(6), 343-355. doi:10.5303/JKAS.2015.48.6.343
• Kim, J. S. (2015). The O- and B- type stellar population in W3: beyond the high-density layer. The Astrophysical Journal, 813, 42.
• Kiminki, M., Kim, J., Bagley, M., Sherry, W., & Rieke, G. (2015). THE O- and B-TYPE STELLAR POPULATION in W3: Beyond the HIGH-DENSITY LAYER. Astrophysical Journal, 813(1). doi:10.1088/0004-637X/813/1/42
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  We present the first results from our survey of the star-forming complex W3, combining VRI photometry with multiobject spectroscopy to identify and characterize the high-mass stellar population across the region. With 79 new spectral classifications, we bring the total number of spectroscopically confirmed O- and B-type stars in W3 to 105. We find that the high-mass slope of the mass function in W3 is consistent with a Salpeter IMF, and that the extinction toward the region is best characterized by an RV of approximately 3.6. B-type stars are found to be more widely dispersed across the W3 giant molecular cloud (GMC) than previously realized: they are not confined to the high-density layer (HDL) created by the expansion of the neighboring W4 H ii region into the GMC. This broader B-type population suggests that star formation in W3 began spontaneously up to 8-10 Myr ago, although at a lower level than the more recent star formation episodes in the HDL. In addition, we describe a method of optimizing sky subtraction for fiber spectra in regions of strong and spatially variable nebular emission.
• Samal, M., Ojha, D., Jose, J., Zavagno, A., Takahashi, S., Neichel, B., Kim, J., Chauhan, N., Pandey, A., Zinchenko, I., Tamura, M., & Ghosh, S. (2015). Star formation in the filament of S254-S258 OB complex: A cluster in the process of being created. Astronomy and Astrophysics, 581. doi:10.1051/0004-6361/201322787
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  Infrared dark clouds are ideal laboratories for studying the initial processes of high-mass star and star-cluster formation. We investigated the star formation activity of an unexplored filamentary dark cloud (size ∼5.7 pc × 1.9 pc), which itself is part of a large filament (∼20 pc) located in the S254-S258 OB complex at a distance of 2.5 kpc. Using Multi-band Imaging Photometer (MIPS) Spitzer 24 μm data, we uncovered 49 sources with signal-to-noise ratios greater than 5. We identified 45 sources as candidate young stellar objects (YSOs) of Class I, flat-spectrum, and Class II natures. Additional 17 candidate YSOs (9 Class I and 8 Class II) are also identified using JHK and Wide-field Infrared Survey Explorer (WISE) photometry. We find that the protostar-to-Class II sources ratio (∼2) and the protostar fraction (∼70%) of the region are high. Comparison of the protostar fraction to other young clusters suggests that the star formation in the dark cloud possibly started only 1 Myr ago. Combining the near-infrared photometry of the YSO candidates with the theoretical evolutionary models, we infer that most of the candidate YSOs formed in the dark cloud are low-mass (
• Kim, J. S. (2014). Sejong Open Cluster Survey (SOS) - III. The young open cluster NGC 1893 in the H II region W8. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. doi:10.1093/mnras/stu1170
• Kim, J. S. (2014). Sejong Open Cluster Survey (SOS) – II. IC 1848 cluster in the H ii region W5 West. MNRAS.
• Sung, H., Lim, B., Bessell, M. S., Kim, J. S., Hur, H., Chun, M., & Park, B. (2014). SEJONG OPEN CLUSTER SURVEY (SOS). 0. TARGET SELECTION AND DATA ANALYSIS. JOURNAL OF THE KOREAN ASTRONOMICAL SOCIETY, 46(3), 103-123.
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  Star clusters are superb astrophysical laboratories containing cospatial and coeval samples of stars with similar chemical composition. We initiate the Sejong Open cluster Survey (SOS) - a project dedicated to providing homogeneous photometry of a large number of open clusters in the SAAO Johnson-Cousins' UBVI system. To achieve our main goal, we pay much attention to the observation of standard stars in order to reproduce the SAAO standard system.
• Fang, M., Kim, J. S., van Boekel, R., Sicilia-Aguilar, A., Henning, T., & Flaherty, K. (2013). YOUNG STELLAR OBJECTS IN LYNDS 1641: DISKS, ACCRETION, AND STAR FORMATION HISTORY. ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 207(1).
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  We investigate the young stellar objects (YSOs) in the Lynds 1641 (L1641) cloud using multi-wavelength data including Spitzer, WISE, the Two Micron All Sky Survey, and XMM covering similar to 1390 YSOs across a range of evolutionary stages. In addition, we targeted a sub-sample of YSOs for optical spectroscopy with the MMT/Hectospec and the MMT/Hectochelle. We use these data, along with archival photometric data, to derive spectral types, extinction values, masses, ages, and accretion rates. We obtain a disk fraction of similar to 50% in L1641. The disk frequency is almost constant as a function of stellar mass with a slight peak at log(M-*/M-circle dot) approximate to -0.25. The analysis of multi-epoch spectroscopic data indicates that the accretion variability of YSOs cannot explain the two orders of magnitude of scatter for YSOs with similar masses. Forty-six new transition disk (TD) objects are confirmed in this work, and we find that the fraction of accreting TDs is lower than for optically thick disks (40%-45% versus 77%-79%, respectively). We confirm our previous result that the accreting TDs have a median accretion rate similar to normal optically thick disks. We confirm that two star formation modes (isolated versus clustered) exist in L1641. We find that the diskless YSOs are statistically older than the YSOs with optically thick disks and the TD objects have a median age that is intermediate between those of the other two populations. We tentatively study the star formation history in L1641 based on the age distribution and find that star formation started to be active 2-3 Myr ago.
• Fang, M., Kim, J., Van Boekel, R., Sicilia-Aguilar, A., Henning, T., & Flaherty, K. (2013). Young stellar objects in lynds 1641: Disks, accretion, and star formation history. Astrophysical Journal, Supplement Series, 207(1). doi:10.1088/0067-0049/207/1/5
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  We investigate the young stellar objects (YSOs) in the Lynds 1641 (L1641) cloud using multi-wavelength data including Spitzer, WISE, the Two Micron All Sky Survey, and XMM covering ∼1390 YSOs across a range of evolutionary stages. In addition, we targeted a sub-sample of YSOs for optical spectroscopy with the MMT/Hectospec and the MMT/Hectochelle. We use these data, along with archival photometric data, to derive spectral types, extinction values, masses, ages, and accretion rates. We obtain a disk fraction of ∼50% in L1641. The disk frequency is almost constant as a function of stellar mass with a slight peak at log (M */M) ≈ -0.25. The analysis of multi-epoch spectroscopic data indicates that the accretion variability of YSOs cannot explain the two orders of magnitude of scatter for YSOs with similar masses. Forty-six new transition disk (TD) objects are confirmed in this work, and we find that the fraction of accreting TDs is lower than for optically thick disks (40%-45% versus 77%-79%, respectively). We confirm our previous result that the accreting TDs have a median accretion rate similar to normal optically thick disks. We confirm that two star formation modes (isolated versus clustered) exist in L1641. We find that the diskless YSOs are statistically older than the YSOs with optically thick disks and the TD objects have a median age that is intermediate between those of the other two populations. We tentatively study the star formation history in L1641 based on the age distribution and find that star formation started to be active 2-3 Myr ago. © 2013. The American Astronomical Society. All rights reserved.
• Hillenbrand, L., Carpenter, J., Kim, J., Meyer, M., Backman, D., Hollenbach, D., Hines, D., Pascucci, I., Bouwman, J., & Moro-Martín, A. (2013). Erratum: The complete census of 70 μm bright debris disks within the feps (formation and evolution of planetary systems) spitzer legacy survey of sun-like stars (Astrophysical Journal (2008) 677 (630)). Astrophysical Journal, 764(1). doi:10.1088/0004-637X/764/1/111
• Jose, J., Pandey, A. K., Samal, M. R., Ojha, D. K., Ogura, K., Kim, J. S., Kobayashi, N., Goyal, A., Chauhan, N., & Eswaraiah, C. (2013). Young stellar population and ongoing star formation in the H ii complex Sh2-252. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 432(4), 3445-3461.
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  In this paper, an extensive survey of the star-forming complex Sh2-252 has been undertaken with an aim to explore its hidden young stellar population as well as to understand the structure and star formation history for the first time. This complex is composed of five prominent embedded clusters associated with the subregions A, C, E, NGC 2175s and Teu 136. We used Two Micron All Sky Survey-near-infrared and Spitzer-Infrared Array Camera, Multiband Imaging Photometer for Spitzer photometry to identify and classify the young stellar objects (YSOs) by their infrared (IR) excess emission. Using the IR colour-colour criteria, we identified 577 YSOs, of which, 163 are Class I, 400 are Class II and 14 are transition disc YSOs, suggesting a moderately rich number of YSOs in this complex. Spatial distribution of the candidate YSOs shows that they are mostly clustered around the subregions in the western half of the complex, suggesting enhanced star formation activity towards its west. Using the spectral energy distribution and optical colour-magnitude diagram-based age analyses, we derived probable evolutionary status of the subregions of Sh2-252. Our analysis shows that the region A is the youngest (similar to 0.5 Myr), the regions B, C and E are of similar evolutionary stage (similar to 1-2 Myr) and the clusters NGC 2175s and Teu 136 are slightly evolved (similar to 2-3 Myr). Morphology of the region in the 1.1 mm map shows a semicircular shaped molecular shell composed of several clumps and YSOs bordering the western ionization front of Sh2-252. Our analyses suggest that next generation star formation is currently under way along this border and that possibly fragmentation of the matter collected during the expansion of the H ii region as one of the major processes is responsible for such stars. We observed the densest concentration of YSOs (mostly Class I, similar to 0.5 Myr) at the western outskirts of the complex, within a molecular clump associated with water and methanol masers and we suggest that it is indeed a site of cluster formation at a very early evolutionary stage, sandwiched between the two relatively evolved CH ii regions A and B.
• Lim, B., Sung, H., Karimov, R., & Ibrahimov, M. (2013). SEJONG OPEN CLUSTER SURVEY. I. NGC 2353. JOURNAL OF THE KOREAN ASTRONOMICAL SOCIETY, 44(2), 39-48.
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  UBVI CCD photometry of NGC 2353 is performed as a part of the "Sejong Open cluster Survey" (SOS). Using photometric membership criteria we selelct probable members of the cluster. We derive the reddening and distance to the cluster, i.e., E(B - V) = 0.10 +/- 0.02 mag and 1.17 +/- 0.04 kpc, respectively. We find that the projected distribution of the probable members on the sky is elliptical in shape rather than circular. The age of the cluster is estimated to be log(age)=8.1 +/- 0.1 in years, older than what was found in previous studies. The minimum value of binary fraction is estimated to be about 48 +/- 5 percent from a Gaussian function fit to the distribution of the distance moduli of the photometric members. Finally, we also obtain the luminosity function and the initial mass function (IMF) of the probable cluster members. The slope of the IMF is Gamma = -1.3 +/- 0.2.
• Lim, B., Sung, H., Kim, J. S., Bessell, M. S., & Karimov, R. (2013). Sejong Open Cluster Survey (SOS) - II. IC 1848 cluster in the HII region W5West. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 438(2), 1451-1465.
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  IC 1848 is one of the young open clusters in the giant star-formingCas OB6association. Several interesting aspects relating to star formation processes in giant star-forming regions attracted us to study the initial mass function (IMF), star formation mode and properties of pre-mains-equence (PMS) stars. A UBVI and H alpha photometric study of the young open cluster IC 1848 was conducted as part of the 'Sejong Open Cluster Survey'. We have selected 105 earlytype members from photometric diagrams. Their mean reddening is < E(B -V)> = 0.660 +/- 0.054 mag. Using the published photometric data with near-and mid-infrared archival data we confirmed the normal reddening law (R-V = 3.1) towards the cluster (IC 1848). A careful zero-age main-sequence fitting gives a distance modulus of V-0 - M-V = 11.7 +/- 0.2mag, equivalent to 2.2 +/- 0.2 kpc. H alpha photometry and the list of young stellar objects identified by Koenig et al. permitted us to select a large number of PMS stars comprising 196 H alpha emission stars, 35 H alpha emission candidates, 5 Class I, 368 Class II and 24 transition disc candidates. From the Hertzsprung-Russell diagram using stellar evolution models, we estimate an age of 5 Myr from several evolved stars and 3 Myr from the PMS stars. The IMF was derived from stars with mass larger than 3M(circle dot), and the slope is slightly steeper (Gamma = -1.6 +/- 0.2) than the Salpeter/Kroupa IMF. Finally, we estimated the mass accretion rate of PMS stars with an ultraviolet excess. The mean mass accretion rate is about 1.4 x 10-8M(circle dot) yr(-1) in the mass range of 0.5-2M(circle dot), whereas intermediate-mass stars (>= 2.5M(circle dot)) exhibit a much higher accretion rate of M > 10(-6)M(circle dot)yr(-1).
• Sicilia-Aguilar, A., Kim, J. S., Sobolev, A., Getman, K., Henning, T., & Fang, M. (2013). The low-mass stellar population in the young cluster Tr 37 Disk evolution, accretion, and environment. ASTRONOMY & ASTROPHYSICS, 559.
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  Aims. We present a study of accretion and protoplanetary disks around M-type stars in the 4 Myr-old cluster Tr 37. With a well-studied solar-type population, Tr 37 is a benchmark for disk evolution.
• Rebull, L., Johnson, C., Hoette, V., Kim, J., Laine, S., Foster, M., Laher, R., Legassie, M., Mallory, C., McCarron, K., & Sherry, W. (2011). New young star candidates in CG4 and Sa101. Astronomical Journal, 142(1). doi:10.1088/0004-6256/142/1/25
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  The CG4 and Sa101 regions together cover a region of ∼0.5deg 2 in the vicinity of a "cometary globule" that is part of the Gum Nebula. There are seven previously identified young stars in this region; we have searched for new young stars using mid- and far-infrared data (3.6-70 μm) from the Spitzer Space Telescope, combined with ground-based optical data and near-infrared data from the Two Micron All Sky Survey. We find infrared excesses in all six of the previously identified young stars in our maps and identify 16 more candidate young stars based on apparent infrared excesses. Most (73%) of the new young stars are Class II objects. There is a tighter grouping of young stars and young star candidates in the Sa101 region, in contrast to the CG4 region, where there are fewer young stars and young star candidates, and they are more dispersed. Few likely young objects are found in the "fingers" of the dust being disturbed by the ionization front from the heart of the Gum Nebula. © 2011. The American Astronomical Society. All rights reserved.
• Roccatagliata, V., Bouwman, J., Henning, T., Gennaro, M., Feigelson, E., Kim, J., Sicilia-Aguilar, A., & Lawson, W. (2011). Disk evolution in ob associations: Deep Spitzer/IRAC observations of IC 1795. Astrophysical Journal, 733(2). doi:10.1088/0004-637X/733/2/113
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  We present a deep Spitzer/Infrared Array Camera (IRAC) survey of the OB association IC 1795 carried out to investigate the evolution of protoplanetary disks in regions of massive star formation. Combining Spitzer/IRAC data with Chandra/Advanced CCD Imaging Spectrometer observations, we find 289 cluster members. An additional 340 sources with an infrared excess, but without X-ray counterpart, are classified as cluster member candidates. Both surveys are complete down to stellar masses of about 1 M⊙. We present pre-main-sequence isochrones computed for the first time in the Spitzer/IRAC colors. The age of the cluster, determined via the location of the Class III sources in the [3.6]-[4.5]/[3.6] color-magnitude diagram, is in the range of 3-5Myr. As theoretically expected, we do not find any systematic variation in the spatial distribution of disks within 0.6 pc of either O-type star in the association. However, the disk fraction in IC 1795 does depend on the stellar mass: sources with masses >2 M⊙ have a disk fraction of ∼ 20%, while lower mass objects (2-0.8 M⊙) have a disk fraction of ∼ 50%. This implies that disks around massive stars have a shorter dissipation timescale. © 2011. The American Astronomical Society. All rights reserved.
• Lo, C. F., Chang, C. Y., Chu, B. H., Kim, H., Kim, J., Cullen, D. A., Zhou, L., Smith, D. J., Pearton, S. J., Dabiran, A., Cui, B., Chow, P. P., Jang, S., & Ren, F. (2010). Proton irradiation effects on AlN/GaN high electron mobility transistors. Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, 28(5), L47-L51. doi:10.1116/1.3482335
• Carpenter, J., Jeroen, B., Mamajek, E., Meyer, M., Hillenbrand, L., Backman, D., Thomas, H., Hines, D., David, H., Jinyoung, S., Amaya, M., Ilaria, P., Silverstone, M., Stauffer, J., & Sebastian, W. (2009). Formation and evolution of planetary systems: properties of debris dust around solar-type stars. Astrophysical Journal, Supplement Series, 181(1), 197-226. doi:10.1088/0067-0049/181/1/197
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  We present Spitzer photometric (IRAC and MIPS) and spectroscopic (IRS low resolution) observations for 314 stars in the Formation and Evolution of Planetary Systems Legacy program. These data are used to investigate the properties and evolution of circumstellar dust around solar-type stars spanning ages from approximately 3 Myr3 Gyr. We identify 46 sources that exhibit excess infrared emission above the stellar photosphere at 24 μm, and 21 sources with excesses at 70 μm. Five sources with an infrared excess have characteristics of optically thick primordial disks, while the remaining sources have properties akin to debris systems. The fraction of systems exhibiting a 24 μm excess greater than 10.2% above the photosphere is 15% for ages < 300 Myr and declines to 2.7% for older ages. The upper envelope to the 70 μm fractional luminosity appears to decline over a similar age range. The characteristic temperature of the debris inferred from the IRS spectra range between 60 and 180 K, with evidence for the presence of cooler dust to account for the strength of the 70 μm excess emission. No strong correlation is found between dust temperature and stellar age. Comparison of the observational data with disk models containing a power-law distribution of silicate grains suggests that the typical inner-disk radius is ≳10 AU. Although the interpretation is not unique, the lack of excess emission shortward of 16 μm and the relatively flat distribution of the 24 μm excess for ages ≲300 Myr is consistent with steady-state collisional models. © 2009. The American Astronomical Society. All rights reserved.
• Diamond-Stanic, A., Fan, X., Brandt, W., Shemmer, O., Strauss, M., Anderson, S., Carilli, C., Gibson, R., Jiang, L., Kim, J., Richards, G., Schmidt, G., Schneider, D., Shen, Y., Smith, P., Vestergaard, M., & Young, J. (2009). High-redshift sdss quasars with weak emission lines. Astrophysical Journal, 699(1). doi:10.1088/0004-637X/699/1/782
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  We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent tail of the Lyα + N v equivalent width distribution, and we compare them to quasars with more typical emission-line properties and to low-redshift active galactic nuclei with weak/absent emission lines, namely BL Lac objects. We find that WLQs exhibit hot (T 1000K) thermal dust emission and have rest-frame 0.1-5 μm spectral energy distributions that are quite similar to those of normal quasars. The variability, polarization, and radio properties of WLQs are also different from those of BL Lacs, making continuum boosting by a relativistic jet an unlikely physical interpretation. The most probable scenario for WLQs involves broad-line region properties that are physically distinct from those of normal quasars. © 2009. The American Astronomical Society.
• Apai, D., Janson, M., Meyer, M., Mamajek, E., Masciadri, E., Henning, T., Pascucci, I., Kim, J., Hillenbrand, L., Kasper, M., Biller, B., & Moro-Martín, A. (2008). A survey for massive giant planets in debris disks with evacuated inner cavities. Astrophysical Journal, 672(2), 1196-1201. doi:10.1086/524191
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  The commonality of collisionally replenished debris around main-sequence stars suggests that minor bodies are frequent around Sun-like stars. Whether or not debris disks in general are accompanied by planets is yet unknown, but debris disks with large inner cavities-perhaps dynamically cleared-are considered to be prime candidates for hosting large-separation massive giant planets. We present here a high-contrast VLT/NACO angular differential imaging survey for eight such cold debris disks. We investigated the presence of massive giant planets in the range of orbital radii where the inner edge of the dust debris is expected. Our observations are sensitive to planets and brown dwarfs with masses >3-7 Jupiter mass, depending on the age and distance of the target star. Our observations did not identify any planet candidates. We compare the derived planet mass upper limits to the minimum planet mass required to dynamically clear the inner disks. While we cannot exclude that single giant planets are responsible for clearing out the inner debris disks, our observations constrain the parameter space available for such planets. The nondetection of massive planets in these evacuated debris disks further reinforces the notion that the giant planet population is confined to the inner disk (
• Bouwman, J., Henning, T., Hillenbrand, L., Meyer, M., Pascucci, I., Carpenter, J., Hines, D., Kim, J., Silverstone, M., Hollenbach, D., & Wolf, S. (2008). The formation and evolution of planetary systems: Grain growth and chemical processing of dust in T tauri systems. Astrophysical Journal, 683(1), 479-498. doi:10.1086/587793
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  This paper is one in a series presenting results obtained within the Formation and Evolution of Planetary Systems (FEPS) Legacy Science Program on the Spitzer Space Telescope. Here we present a study of dust processing and growth in seven protoplanetary disks. Our spectra indicate that the circumstellar silicate dust grains have grown to sizes at least 10 times larger than observed in the interstellar medium and show evidence for a non-negligible (∼5% in mass fractions) contribution from crystalline species. These results are similar to those of other studies of protoplanetary disks. In addition, we find a correlation between the strength of the amorphous silicate feature and the shape of the spectral energy distribution. This latter result is consistent with the growth and subsequent gravitational settling of dust grains toward the disk midplane. Furthermore, we find a change in the relative abundance of the different crystalline species: more enstatite than forsterite is observed in the inner warm dust population at ∼1 AU, while forsterite dominates in the colder outer regions at ∼5-15 AU. This change in the relative abundances argues for a localized crystallization process rather than a radial mixing scenario in which crystalline silicates are being transported outwards from a single formation region in the hot inner parts of the disk. Finally, we report the detection of emission from polycyclic aromatic hydrocarbon (PAH) molecules in five out of seven sources. We find a tentative PAH band at 8.2 μm that was previously undetected in the spectra of disks around low-mass pre-main-sequence stars. © 2008. The American Astronomical Society. All rights reserved.
• Carpenter, J., Bouwman, J., Silverstone, M., Kim, J., Stauffer, J., Cohen, M., Hines, D., Meyer, M., & Crockett, N. (2008). The formation and evolution of planetary systems: Description of the Spitzer Legacy science database. Astrophysical Journal, Supplement Series, 179(2). doi:10.1086/592274
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  We present the science database produced by the Formation and Evolution of Planetary Systems (FEPS) Spitzer Legacy program. Data reduction and validation procedures for the IRAC, MIPS, and IRS instruments are described in detail. We also derive stellar properties for the FEPS sample from available broadband photometry and spectral types, and present an algorithm to normalize Kurucz synthetic spectra to optical and near-infrared photometry. The final FEPS data products include IRAC and MIPS photometry for each star in the FEPS sample and calibrated IRS spectra. © 2008. The American Astronomical Society. All rights reserved.
• Hillenbrand, L., Carpenter, J., Kim, J., Meyer, M., Backman, D., Hollenbach, D., Hines, D., Pascucci, I., Bouwman, J., & Moro-Martín, A. (2008). The complete census of 70 μm-bright debris disks within "the formation and evolution of planetary systems" Spitzer legacy survey of sun-like stars. Astrophysical Journal, 677(1). doi:10.1086/529027
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  We report detection of cool dust surrounding solar-type stars from observations performed as part of the Spitzer Legacy Science Program FEPS. From a sample of 328 stars having ages ∼0.003-3 Gyr we have selected sources with 70 μm flux densities indicating excess in their SEDs above expected photospheric emission. Six strong excess sources are likely primordial circumstellar disks, remnants of the star formation process. Another 25 sources having ≥3 σ excesses are associated with dusty debris disks, generated by collisions within planetesimal belts that are possibly stirred by existing planets. Six additional sources with ≥2 σ excesses require confirmation as debris disks. In our analysis, most (>80%) 70 μm excess sources have ≥3 σ excesses at 33 μm as well, while only a minority (
• Meyer, M., Carpenter, J., Mamajek, E., Hillenbrand, L., Hollenbach, D., Moro-Martin, A., Kim, J., Silverstone, M., Najita, J., Hines, D., Pascucci, I., Stauffer, J., Bouwman, J., & Backman, D. (2008). Evolution of mid-infrared excess around sun-like stars: Constraints on models of terrestrial planet formation. Astrophysical Journal, 673(2), L181. doi:10.1086/527470
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  We report observations from the Spitzer Space Telescope regarding the frequency of 24 μm excess emission toward Sun-like stars. Our unbiased sample is composed of 309 stars with masses 0.7-2.2 M⊙, and ages from 3 Gyr that lack excess emission at wavelengths ≤8 μm. We identify 30 stars that exhibit clear evidence of excess emission from the observed 24 mm/8 μm flux ratio. The implied 24 μm excesses of these candidate debris disk systems range from 13% (the minimum detectable) to more than 100% compared to the expected photospheric emission. The frequency of systems with evidence for dust debris emitting at 24 μm ranges from 8.5% - 19% at ages
• Pascucci, I., Apai, D., Hardegree-Ullman, E., Kim, J., Meyer, M., & Bouwman, J. (2008). Medium-separation binaries do not affect the first steps of planet formation. Astrophysical Journal, 673(1). doi:10.1086/524100
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  The first steps of planet formation are marked by the growth and crystallization of sub-micrometer-sized dust grains accompanied by dust settling toward the disk midplane. In this paper we explore whether the first steps of planet formation are affected by the presence of medium-separation stellar companions. We selected two large samples of disks around single and binary T Tauri stars in Taurus that are thought to have only a modest age spread of a few Myr. The companions of our binary sample are at projected separations between ∼ 10 and 450 AU, with masses down to about 0.1 M⊙. We used the strength and shape of the 10 μm silicate emission feature as a proxy for grain growth and for crystallization, respectively. The degree of dust settling was evaluated from the ratio of fluxes at two different mid-infrared wavelengths. We find no statistically significant difference between the distribution of 10 μm silicate emission features from single and binary systems. In addition, the distribution of disk flaring is indistinguishable between the single and binary system samples. These results show that the first steps of planet formation are not affected by the presence of a companion at tens of AU. © 2008. The American Astronomical Society. All rights reserved.
• Kim, J. S., Bouwman, J., Carpenter, J. M., Henning, T., Hillenbrand, L. A., Hines, D. C., Hollenbach, D., Lunine, J. I., Malhotra, R., Mamajek, E. E., Meyer, M. R., Moro-martin, A., Najita, J. R., Pascucci, I., Silverstone, M. D., & Wolf, S. (2007).

  Are Debris Disks and Massive Planets Correlated

  . The Astrophysical Journal, 658(2), 1312-1321. doi:10.1086/511746
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  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.
• Pascucci, I., Hollenbach, D., Najita, J., Muzerolle, J., Gorti, U., Herczeg, G., Hillenbrand, L., Kim, J., Carpenter, J., Meyer, M., Mamajek, E., & Bouwman, J. (2007). Detection of [Ne II] emission from young circumstellar disks. Astrophysical Journal, 663(1 I). doi:10.1086/518535
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  We report the detection of [Ne II] emission at 12.81 μ in four out of the six optically thick dust disks observed as part of the FEPS Spitzer Legacy program. In addition, we detect a H I (7-6) emission line at 12.37 μm from the source RX J 1852.3-3700. Detections of [Ne II] lines are favored by low mid-infrared excess emission. Both stellar X-rays and extreme ultraviolet (EUV) photons can sufficiently ionize the disk surface to reproduce the observed line fluxes, suggesting that emission from Ne+ originates in the hot disk atmosphere. On the other hand, the H I (7-6) line is not associated with the gas in the disk surface, and magnetospheric accretion flows can account for at most ∼30% of the observed flux. We conclude that accretion shock regions and/or the stellar corona could contribute to most of the H I (7-6) emission. Finally, we discuss the observations necessary to identify whether stellar X-rays or EUV photons are the dominant ionization mechanism for Ne atoms. Because the observed [Ne II] emission probes very small amounts of gas in the disk surface ∼ 10-6 MJ ) we suggest using this gas line to determine the presence or absence of gas in more evolved circumstellar disks. © 2007. The American Astronomical Society. All rights reserved.
• Hines, D., Backman, D., Bouwman, J., Hillenbrand, L., Carpenter, J., Meyer, M., Kim, J., Silverstone, M., Rodmann, J., Wolf, S., Mamajek, E., Brooke, T., Padgett, D., Henning, T., Stobie, E., Gordon, K., Morrison, J., Muzerolle, J., Su, K., & Moro-Martín, A. (2006). The Formation and Evolution of Planetary Systems (FEPS): Discovery of an unusual debris system associated with HD 12039. Astrophysical Journal, 638(2 I). doi:10.1086/498929
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  We report the discovery of a debris system associated with the ∼30 Myr old G3/5V star HD 12039 using Spitzer Space Telescope observations from 3.6-160 μm. An observed infrared excess (LIR/L* = 1 × 10 -4) above the expected photosphere for λ ≳ 14 μm is fit by thermally emitting material with a color temperature of T ∼ 110K, warmer than the majority of debris disks identified to date around Sun-like stars. The object is not detected at 70 μm with a 3 σ upper limit 6 times the expected photospheric flux. The spectrum of the infrared excess can be explained by warm, optically thin material comprised of blackbody-like grains of size ≳7 μm that reside in a belt orbiting the star at 4-6 AU. An alternate model dominated by smaller grains, near the blowout size a ∼ 0.5 μm, located at 30-40 AU is also possible but requires the dust to have been produced recently, since such small grains will be expelled from the system by radiation pressure in approximately a few times 102 yr. © 2006. The American Astronomical Society. All rights reserved.
• Meyer, M., Hillenbrand, L., 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., 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. doi:10.1086/510099
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  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., Carpenter, J., Hillenbrand, L., Herczeg, G., Padgett, D., Mamajek, E., Silverstone, M., Schlingman, W., Kim, J., Stobie, E., Bouwman, J., Wolf, S., Rodmann, J., Hines, D., 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, 651(2 I), 1177-1193. doi:10.1086/507761
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  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
• Silverstone, M., Meyer, M., Mamajek, E., Hines, D., Hillenbrand, L., Najita, J., Pascucci, I., Bouwman, J., Kim, J., Carpenter, J., Stauffer, J., Backman, D., Moro-Martin, A., Henning, T., Wolf, S., Brooke, T., & Padgett, D. (2006). Formation and Evolution of Planetary Systems (FEPS): Primordial warm dust evolution from 3 to 30 Myr around Sun-like stars. Astrophysical Journal, 639(2 I), 1138-1146. doi:10.1086/499418
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  We present data obtained with the Infrared Array Camera (IRAC) aboard the Spitzer Space Telescope (Spitzer) for a sample of 74 young (t < 30 Myr old) Sun-like (0.7 < M*/M⊙ < 1.5) stars. These are a subset of the observations that comprise the Spitzer Legacy science program entitled the Formation and Evolution of Planetary Systems (FEPS). Using IRAC, we study the fraction of young stars that exhibit 3.6-8.0 μm infrared emission in excess of that expected from the stellar photosphere, as a function of age from 3 to 30 Myr. The most straightforward interpretation of such excess emission is the presence of hot (300-1000 K) dust in the inner regions (
• Hollenbach, D., Gorti, U., Meyer, M., Kim, J., Morris, P., Najita, J., Pascucci, I., Carpenter, J., Rodmann, J., Brooke, T., Hillenbrand, L., Mamajek, E., Padgett, D., Soderblom, D., Wolf, S., & Lunine, J. (2005). Formation and evolution of planetary systems: Upper limits to the gas mass in HD 105. Astrophysical Journal, 631(2 I), 1180-1190. doi:10.1086/432638
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  We report infrared spectroscopic observations of HD 105, a nearby (∼40 pc) and relatively young (∼30 Myr) GO star with excess infrared continuum emission, which has been modeled as arising from an optically thin circumstellar dust disk with an inner hole of size ≳13 AU. We have used the high spectral resolution mode of the Infrared Spectrometer (IRS) on the Spitzer Space Telescope to search for gas emission lines from the disk. The observations reported here provide upper limits to the fluxes of H2 S(0) 28 μm, H2 S(1) 17 μm, H2 S(2) 12 μm, [Fe II] 26 μm, [Si II] 35 μm, and [S I] 25 μm infrared emission lines. The H2 line upper limits place direct constraints on the mass of warm molecular gas in the disk: M(H2) < 4.6, 3.8 × 10-2, and 3.0 × 10-3 MJ at T = 50, 100, and 200 K, respectively. We also compare the line flux upper limits to predictions from detailed thermal/chemical models of various gas distributions in the disk. These comparisons indicate that if the gas distribution has an inner hole with radius ri,gas, the surface density at that inner radius is limited to values ranging from ≲3 g cm-2 at ri,gas = 0.5 AU to 0.1 g cm-2 at ri,gas = 5-20 AU. These values are considerably below the value for a minimum mass solar nebula, and suggest that less than 1 Jupiter mass (MJ) of gas (at any temperature) exists in the 1-40 AU planet-forming region. Therefore, it is unlikely that there is sufficient gas for gas giant planet formation to occur in HD 105 at this time. © 2005. The American Astronomical Society. All rights reserved.
• Kim, J., Walter, F., & Wolk, S. (2005). Low-mass star formation in the gum nebula: The CG 30/31/38 complex. Astronomical Journal, 129(3), 1564-1579. doi:10.1086/428002
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  We present photometric and spectroscopic results for the low-mass pre-main-sequence (PMS) stars with spectral types K-M in the cometary globule (CG) 30/31/38 complex. We obtained multiobject high-resolution spectra for the targets selected as possible PMS stars from multiwavelength photometry. We identified 11 PMS stars brighter than V = 16.5 with ages ≲5 Myr at a distance of approximately 200 pc. The spatial distribution of the PMS stars, CG clouds, and ionizing sources (0 stars and supernova remnants) suggests a possible triggered origin of the star formation in this region. We confirm the youth of the photometrically selected PMS stars using the lithium abundances. The radial velocities of the low-mass PMS stars are consistent with those of the cometary globules. Most of the PMS stars show weak Hα emission with W λ(Hα) < 10 Å. Only one out of the 11 PMS stars shows a moderate near-IR excess, which suggests a short survival time (t < 5 Myr) of circumstellar disks in this star-forming environment. In addition, we find five young late-type stars and one Ae star that have no obvious relation to the CG 30/31/38 complex. We also discuss a possible scenario of the star formation history in the CG 30/31/38 region. © 2005. The American Astronomical Society. All rights reserved.
• Stauffer, J., Rebull, L., Carpenter, J., Hillenbrand, L., Backman, D., Meyer, M., Kim, J., Silverstone, M., Young, E., Hines, D., Soderblom, D., Mamajek, E., Morris, P., Bouwman, J., & Strom, S. (2005). Spitzer Space Telescope observations of G dwarfs in the Pleiades: Circumstellar debris disks at 100 Myr age. Astronomical Journal, 130(4), 1834-1844. doi:10.1086/444420
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  Fluxes and upper limits in the wavelength range from 3.6 to 70 μ from the Spitzer Space Telescope are provided for 20 solar-mass Pleiades members. One of these stars shows a probable mid-IR excess, and two others have possible excesses, presumably due to circumstellar debris disks. For the star with the largest, most secure excess flux at MIPS (Multiband Imaging Photometer for Spitzer) wavelengths, HII 1101, we derive log (Ldust/L*) ∼ -3.8 and an estimated debris disk mass of 4.2 × 10-5 M ⊕ for an assumed uniform dust grain size of 10 μm. If the stars with detected excesses are interpreted as stars with relatively recent, large collisional events producing a transient excess of small dust particles, the frequency of such disk transients is ∼10% for our ∼100 Myr, Pleiades G dwarf sample. For the stars without detected 24-70 μm excesses, the upper limits to their fluxes correspond to approximate 3 σ upper limits to their disk masses of 6 × 10-6 M⊕ using the MIPS 24 μm upper limit or 2 × 10-4 M⊕ using the MIPS 70 μm limit. These upper limit disk masses (for "warm" and "cold" dust, respectively) are roughly consistent with, but somewhat lower than, predictions of a heuristic model for the evolution of an "average" solar-mass star's debris disk based on extrapolation backward in time from current properties of the Sun's Kuiper Belt. © 2005. The American Astronomical Society. All rights reserved.
• Meyer, M., Hillenbrand, L., Backman, D., Beckwith, S., Bouwman, J., Brooke, T., Carpenter, J., Cohen, M., Gorti, U., Henning, T., Hines, D., Hollenbach, D., Kim, J., Lunine, J., Malhotra, R., Mamajek, 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. doi:10.1086/423177
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  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.

Proceedings Publications

• Hamden, E., Schiminovich, D., Turner, N., Burkhart, B., Haworth, T., Arulanantham, N., Chung, H., Kong, S., Hoadley, K., Willacy, K., Dharmawardena, T., Kim, J., Bialy, S., Lee, M., Smith, M., & Luthman, E. (2024, 08). Eos: a FUV spectroscopic mission to observe molecular hydrogen in molecular clouds. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 13093, 130930C.
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  Eos is a mission concept to be proposed to the expected 2025 NASA Small Explorers Announcement of Opportunity (SMEX AO). Eos observes molecular clouds in our galaxy and nearby planet forming disks to understand the link between star and planet formation and molecular hydrogen in galactic star forming regions. Eos does this using very long-slit, high resolution spectroscopy of far ultraviolet (FUV) emission from fluorescent molecular hydrogen (H2), a powerful and underutilized FUV diagnostic. H2 is the most abundant molecule in the universe, but is typically observed in the infrared (IR) or inferred via proxies such as CO. Eos will directly observe H2 via fluorescence, which can be stimulated from a range of sources (shocks, interstellar UV radiation, bright stars, etc). Here we briefly describe the science objectives of Eos, as well as the instrument implementation.
• Kim, J., Fang, M., Eisner, J., Pascucci, I., Apai, D., Clarke, C., Facchini, S., Manara, C., Kounkel, M., & Covey, K. (2018, jul). Probing Effect of External UV Radiation on Young Stellar and Substellar Mass Objects: Is Orion a Special Place for Observing External Photoevaporation of Disks?. In 20th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun.
• Kim, J. S., Fang, M., Fang, M., Facchini, S., Pascucci, I., Apai, D., Bally, J., Clarke, C. J., Clarke, C. J., & Kim, J. S. (2017). Young stellar objects & photoevaporating protoplanetary disks in the Orion's sibling NGC 1977.. In Francesco's legacy in education and outreach.
• Kim, J., Pascucci, I., Allen, L., Apai, D., Bergin, T., Ciesla, F., Eisner, J., Fang, M., Krijt, S., Najita, J., Rieke, G., & Salyk, C. (2017, nov). Earths in Other Solar Systems: Fundamental Protoplanetary Disk Properties and Their Evolution. In LPI Contributions, 2042, 4071.
• Kim, J. S. (2014, 8). Disk Evolution of Young Stellar Objects in Lynds 1641. In The 10th Pacific Rim Conference on Stellar Astrophysics.

Presentations

• Kim, J. S. (2020, February 11-13). Probing Star formation & UV environment with Spitzer. Celebrating the Legacy of the Spitzer Space Telescope. Pasadena, California: California Institute of Technology,.
• Kim, J. S. (2020, November). Observations of external photoevaporation at intermediate UV radiation: Proplyds. Threats from the Surroundings. e-conference: European Southern Observatory.
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  Invited speaker for a conference, "Threats from the Surroundings" - an e-workshop on the importance of environment for the evolution of protoplanetary discs and formation of planetshttps://www.eso.org/sci/meetings/2020/tfts2020/invited.html
• Kim, J. S. (2020, November). Protoplanetary Disks in Diverse Star Forming Environments. Colloquium talk for School of Physics and Astronomy, Queen Mary University of London, London, UK. e-colloquium via zoom; Queen Mary University of London, London, UK: Queen Mary University of London, London, UK.
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  Colloquium talk for School of Physics and Astronomy, Queen Mary University of London, London, UK
• Kim, J. S. (2020, October 7). Astronomy in University of Arizona. Daegu National Science Center - Talk Concert (South Korea). via Zoom (South Korea - nationwide program by Daegu National Science Center): Daegu National Science Center, Daegu, South Korea.
• Kim, J. S. (2019, February). Observing with MMT: Available Instruments and Science Highlights. KGMT Users meeting. Daejeon, Korea: Korea Asstronomy and Space Science Institute (KASI).
• Kim, J. S. (2019, May). MMT's Powerful Large Field of View Multi-Object Spectroscopy Probes Star Formation in the Milky Way. MMT Observatory's 40th Anniversary Symposium and Celebration. University of Arizona: MMT.
• Kim, J. S., & Fang, M. (2019, September). Characterizing properties of accreting young stars in the Orion Nebula Cluster (Trapezium cluster). NExSS EOS team (Earth in Other Solar System) All Hands Meeting. Tucson, AZ: NExSS EOS team (Steward Observatory/Univ. of Arizona).
• Kim, J. S., Pascucci, I., Apai, D., & Eisner, J. A. (2017, November). EARTHS IN OTHER SOLAR SYSTEMS: FUNDAMENTAL PROTOPLANETARY DISK PROPERTIES AND THEIR EVOLUTION. Habitable Worlds 2017: A System Science Workshop (NASA NExSS workshop). Laramie, WY: NASA - the Nexus for Exoplanet System Science (NExSS).
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  The Nexus for Exoplanet System Science (NExSS), a NASA research coordination network dedicated to the study of planetary habitability held a five-day workshop on Habitable Worlds 2017: A System Science Workshop, November 13–17, 2017 at the University of Wyoming Conference Center (UWCC) and Marian H. Rochelle Gateway Center (MHRGC) in Laramie, Wyoming. I was one of the local organization committee and also served to select scientific programs.
• Kim, J. S. (2015, April). Building on successful existing collaborations with the University of Arizona. Korean Astronimical Society 50th year anniversary meeting. Seoul National University.
• Kim, J. S. (2014, March, 2014). Probing triggered star formation: young stars associated with AFGL333 in W3. Search for Life Beyond the Solar System. Exoplanets, Biosignatures & Instruments.

Poster Presentations

• Kim, J. S. (2021, February). External Photoevaporation of Protoplanetary Disks in Intermediate UV Environments NGC 1977 and NGC 2024. Conference: Habitable World 2021. on-line: AAS, NASA/NExSS.
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  In coordination with the American Astronomical Society (AAS), the Nexus for Exoplanet System Science (NExSS) is pleased to announce the AAS Topical Conference: Habitable Worlds 2021 (HabWorlds2). The goal of the workshop is to identify opportunities and obstacles to cross-disciplinary collaboration on the questions of what makes planets habitable, and life on them detectable. The culminating event will be a synchronous, online conference 22-26 February 2021.
• Kim, J. S. (2021, March). External Photoevaporation of Disks around Low Mass Young Stellar and Sub-Stellar Objects. Conference: Cool Stars 20.5. on-line: Harvard Smithsonian Center for Astrophysics (CfA) & MIT Kavli Institute.
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  https://zenodo.org/record/4568081#.YH5CUxNKjUI
• James, M., Kim, J., & Bally, J. (2019, jan). Variability of Ten Silhouette Disks in the Orion Nebula Cluster in Ten Years. American Astronomical Society Meeting Abstracts #233.
• Wentzel-Long, M. .., Wilking, B., Kim, J., & Bryan, J. (2019, jan). Investigating Circumstellar Disk Destruction in the HII Region W4. American Astronomical Society Meeting Abstracts #233.
• Kim, J. S., Apai, D., Fang, M., Pascucci, I., Fang, M., Pascucci, I., Apai, D., & Kim, J. S. (2017, June). Fantastic YSOs and photoevaporating protoplanetary disks in the Orion’s sibling - NGC 1977. Francesco's Legacy: Star Formation in Space and Time. Florence, Italy: Osservatorio Astrofisico di Arcetri.

Others

• Kim, J. S. (2016, 12). A Spitzer Space Telescope Survey for Dusty Debris Disks in the Nearby 32 Orionis Group. Astro-ph. http://arxiv.org/abs/1612.06924v1
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  We report Spitzer Space Telescope IRAC 3.6, 4.5, 5.8 and 8 um and MIPS 24 and70 um observations of the 32 Ori Group, a recently discovered nearby stellarassociation situated towards northern Orion. The proximity of the group (~93pc) has enabled a sensitive search for circumstellar dust around group members,and its age (~20 Myr) corresponds roughly to an epoch thought to be importantfor terrestrial planet formation in our own solar system. We quantify infraredexcess emission due to circumstellar dust among group members, utilizingavailable optical (e.g. Hipparcos, Tycho) and near-IR (2MASS) photometry inaddition to the Spitzer IR photometry. We report 4 out of the 14 objects whichexhibit 24 um excess emission more than 4\sigma above the stellar photosphere(>20%) though lacking excess emission at shorter wavelengths: HD 35656 (A0Vn),HD 36338 (F4.5), RX J0520.5+0616 (K3), and HD 35499 (F4). Two objects (HD 35656and RX J0520.0+0612) have 70 um excesses, although the latter lacks 24 umexcess emission. The 24 um disk fraction of this group is 29(+14,-9%), which issimilar to previous findings for groups of comparable ages and places 32 Ori asthe young stellar group with the 2nd most abundant 24 um excesses among groupslacking accreting T Tauri stars (behind only the approximately coeval Beta PicMoving Group). We also model the infrared excess emission using circumstellardust disk models, placing constraints on disk parameters including L_IR/L_*,T_disk, characteristic grain distance, and emitting area. The L_IR/L_* valuesfor all the stars can be reasonably explained by steady state disk evolution.[Journal_ref: ]
• Sung, H., Lim, B., Bessell, M. S., Kim, J. S., Hur, H., Chun, M., & Park, B. (2011, OCT 31). SEJONG OPEN CLUSTER SURVEY (SOS). 0. TARGET SELECTION AND DATA ANALYSIS (vol 46, pg 103, 2013). JOURNAL OF THE KOREAN ASTRONOMICAL SOCIETY.