Daniel Apai

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Scholarly Contributions

Journals/Publications

• 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.
• Lew, B. W., Apai, D., Zhou, Y., Marley, M., Mayorga, L., Tan, X., Parmentier, V., Casewell, S., & Xu, (. S. (2022). Mapping the Pressure-dependent Day-Night Temperature Contrast of a Strongly Irradiated Atmosphere with HST Spectroscopic Phase Curve. \aj, 163(1), 8.
• Rackham, B. V., Espinoza, N., Berdyugina, S. V., Korhonen, H., MacDonald, R. J., Montet, B. T., Morris, B. M., Oshagh, M., Shapiro, A. I., Unruh, Y. C., Quintana, E. V., Zellem, R. T., Apai, D., Barclay, T., Barstow, J. K., Bruno, G., Carone, L., Casewell, S. L., Cegla, H. M., , Criscuoli, S., et al. (2022). Final Report for SAG 21: The Effect of Stellar Contamination on Space-based Transmission Spectroscopy. arXiv e-prints, arXiv:2201.09905.
• Wagner, K., Apai, D., Kasper, M., McClure, M., & Robberto, M. (2022). The Scorpion Planet Survey: Wide-orbit Giant Planets Around Young A-type Stars. \aj, 163(2), 80.
• Zhou, Y., Apai, D., Tan, X., Lothringer, J. D., Lew, B. W., Casewell, S. L., Parmentier, V., Marley, M. S., Xu, S., & Mayorga, L. (2022). HST/WFC3 Complete Phase-resolved Spectroscopy of White-dwarf-brown-dwarf Binaries WD 0137 and EPIC 2122. \aj, 163(1), 17.
• Apai, D., Nardiello, D., & Bedin, L. R. (2021). "TESS Observations of the Luhman 16 AB Brown Dwarf System: Rotational Periods, Lightcurve Evolution, and Zonal Circulation". apj, 906(1), 64.
• Biller, B. A., Apai, D., Bonnefoy, M., Desidera, S., Gratton, R., Kasper, M., Kenworthy, M., Lagrange, A., Lazzoni, C., Mesa, D., Vigan, A., Wagner, K., Vos, J. M., & Zurlo, A. (2021). "A high-contrast search for variability in HR 8799bc with VLT-SPHERE". mnras, 503(1), 743-767.
• Bixel, A., & Apai, D. (2021). "Bioverse: a simulation framework to assess the statistical power of future biosignature surveys". arXiv e-prints, arXiv:2101.10393.
• Bixel, A., & Apai, D. (2021). Bioverse: A Simulation Framework to Assess the Statistical Power of Future Biosignature Surveys. \aj, 161(5), 228.
• Carone, L., Molli{`ere}, P., Zhou, Y., Bouwman, J., Yan, F., Baeyens, R., Apai, D., Espinoza, N., Rackham, B. V., Jord{'an}, A., Angerhausen, D., Decin, L., Lendl, M., Venot, O., & Henning, T. (2021). "Indications for very high metallicity and absence of methane in the eccentric exo-Saturn WASP-117b". aap, 646, A168.
• Dietrich, J., & Apai, D. (2021). "An Integrated Analysis with Predictions on the Architecture of the {ensuremath{tau} Ceti Planetary System, Including a Habitable Zone Planet}". aj, 161(1), 17.
• Fang, M., Kim, J. S., Pascucci, I., & Apai, D. (2021). "An Improved Hertzsprung-Russell Diagram for the Orion Trapezium Cluster". apj, 908(1), 49.
• Kirk, J., Rackham, B. V., MacDonald, R. J., L{\'opez-Morales}, M., Espinoza, N., Lendl, M., Wilson, J., Osip, D. J., Wheatley, P. J., Skillen, I., Apai, D., Bixel, A., Gibson, N. P., Jord{\'an}, A., Lewis, N. K., Louden, T., McGruder, C. D., Nikolov, N., Rodler, F., & Weaver, I. C. (2021). ACCESS and LRG-BEASTS: A Precise New Optical Transmission Spectrum of the Ultrahot Jupiter WASP-103b. \aj, 162(1), 34.
• Lin, C., Chen, W., Ip, W., Apai, D., Bixel, A., Boyle, R., Chavez, J. P., Espinoza, N., Gibbs, A., Gabor, P., Henning, T., Mancini, L., Rackham, B. V., Schlecker, M., Dietrich, J., Socia, Q. J., Keppler, M., Bhandare, A., & H{\"aberle}, M. (2021). EDEN: Flare Activity of the Nearby Exoplanet-hosting M Dwarf Wolf 359 Based on K2 and EDEN Light Curves. \aj, 162(1), 11.
• Quintana, E. V., Col{\'on}, K. D., Mosby, G., Schlieder, J. E., Supsinskas, P., Karburn, J., Dotson, J. L., Greene, T. P., Hedges, C., Apai, D., Barclay, T., Christiansen, J. L., Espinoza, N., Mullally, S. E., Gilbert, E. A., Hoffman, K., Kostov, V. B., Lewis, N. K., Foote, T. O., , Mason, J., et al. (2021). The Pandora SmallSat: Multiwavelength Characterization of Exoplanets and their Host Stars. arXiv e-prints, arXiv:2108.06438.
• Scalco, M., Bellini, A., Bedin, L., Anderson, J., Rosati, P., Libralato, M., Salaris, M., Vesperini, E., Nardiello, D., Apai, D., Burgasser, A., & Gerasimov, R. (2021). The HST large programme on \ensuremath{\omega} Centauri - IV. Catalogue of two external fields. \mnras, 505(3), 3549-3561.
• Schlawin, E., Su, K. Y., Herter, T., Ridden-Harper, A., & Apai, D. (2021). LBT Reveals Large Dust Particles and a High Mass-loss Rate for K2-22 b. \aj, 162(2), 57.
• Tannock, M. E., Metchev, S., Heinze, A., Miles-P{'aez}, P. A., Gagn{'e}, J., Burgasser, A., Marley, M. S., Apai, D., Su{'arez}, G., & Plavchan, P. (2021). "Weather on Other Worlds. V. The Three Most Rapidly Rotating Ultra-Cool Dwarfs". arXiv e-prints, arXiv:2103.01990.
• Tannock, M. E., Metchev, S., Heinze, A., Miles-P{\'aez}, P. A., Gagn{\'e}, J., Burgasser, A., Marley, M. S., Apai, D., Su{\'arez}, G., & Plavchan, P. (2021). Weather on Other Worlds. V. The Three Most Rapidly Rotating Ultra-cool Dwarfs. \aj, 161(5), 224.
• Wagner, K., Boehle, A., Pathak, P., Kasper, M., Arsenault, R., Jakob, G., K{"aufl}, U., Leveratto, S., Maire, A. -., Pantin, E., Siebenmorgen, R., Zins, G., Absil, O., Ageorges, N., Apai, D., Carlotti, A., Choquet, '., Delacroix, C., Dohlen, K., , Duhoux, P., et al. (2021). "Imaging low-mass planets within the habitable zone of {ensuremath{alpha} Centauri}". Nature Communications, 12, 922.
• Weaver, I. C., L{\'opez-Morales}, M., Alam, M. K., Espinoza, N., Rackham, B. V., Goyal, J. M., MacDonald, R. J., Lewis, N. K., Apai, D., Bixel, A., Jord{\'an}, A., Kirk, J., McGruder, C., & Osip, D. J. (2021). ACCESS: An Optical Transmission Spectrum of the High-gravity Hot Jupiter HAT-P-23b. \aj, 161(6), 278.
• Wells, R., Rackham, B., Schanche, N., Petrucci, R., G{\'omez, M., Demory, B. -., Burgasser, A., Burn, R., Pozuelos, F., G{\"unther}, M., Sabin, L., Schroffenegger, U., G{\'omez-Mu\~noz}, M., Stassun, K., Van Grootel, V., Howell, S., Sebastian, D., Triaud, A., Apai, D., , Plauchu-Frayn, I. .., et al. (2021). A large sub-Neptune transiting the thick-disk M4 V TOI-2406. \aap, 653, A97.
• Zhou, Y., Bowler, B. P., Wagner, K. R., Schneider, G., Apai, D., Kraus, A. L., Close, L. M., Herczeg, G. J., & Fang, M. (2021). Hubble Space Telescope UV and H\ensuremath{\alpha} Measurements of the Accretion Excess Emission from the Young Giant Planet PDS 70 b. \aj, 161(5), 244.
• Bixel, A., & Apai, D. (2020). "Identifying Exo-Earth Candidates in Direct Imaging Data through Bayesian Classification". aj, 159(1), 3.
• Bixel, A., & Apai, D. (2020). "Testing Earthlike Atmospheric Evolution on Exo-Earths through Oxygen Absorption: Required Sample Sizes and the Advantage of Age-based Target Selection". apj, 896(2), 131.
• Burgasser, A. J., Lowrance, P. J., Bedin, L. R., Karalidi, T., Manjavacas, E., Miles-Páez, P. A., Cowan, N. B., Schneider, G., Marley, M., Radigan, J., Zhou, Y., Apai, D., & Lew, B. W. (2020). Cloud Atlas: Weak Color Modulations Due to Rotation in the Planetary-mass Companion GU Psc b and 11 Other Brown Dwarfs. Astronomical Journal, 159, 125. doi:2020AJ....159..125L
• Dietrich, J., & Apai, D. (2020). "Hidden Worlds: Dynamical Architecture Predictions of Undetected Planets in Multi-planet Systems and Applications to TESS Systems". aj, 160(3), 107.
• Gibbs, A., Bixel, A., Rackham, B. V., Apai, D., Schlecker, M., Espinoza, N., Mancini, L., Chen, W., Henning, T., Gabor, P., Boyle, R., Perez, C. J., Mousseau, A., Dietrich, J., Jay, S. Q., Ip, W., Ngeow, C., Tsai, A., Bhandare, A., , Marian, V., et al. (2020). "EDEN: Sensitivity Analysis and Transiting Planet Detection Limits for Nearby Late Red Dwarfs". aj, 159(4), 169.
• Kitzmann, D., Heng, K., Oreshenko, M., Grimm, S. L., Apai, D., Bowler, B. P., Burgasser, A. J., & Marley, M. S. (2020). "Helios-r2: A New Bayesian, Open-source Retrieval Model for Brown Dwarfs and Exoplanet Atmospheres". apj, 890(2), 174.
• Lew, B. W., Apai, D., Marley, M., Saumon, D., Schneider, G., Zhou, Y., Cowan, N. B., Karalidi, T., Manjavacas, E., Bedin, L., & Miles-P{'aez}, P. A. (2020). "Cloud Atlas: Unraveling the Vertical Cloud Structure with the Time-series Spectrophotometry of an Unusually Red Brown Dwarf". apj, 903(1), 15.
• Lew, B. W., Apai, D., Zhou, Y., Radigan, J., Marley, M., Schneider, G., Cowan, N. B., Miles-P{'aez}, P. A., Manjavacas, E., Karalidi, T., Bedin, L., Lowrance, P. J., & Burgasser, A. J. (2020). "Cloud Atlas: Weak Color Modulations Due to Rotation in the Planetary-mass Companion GU Psc b and 11 Other Brown Dwarfs". aj, 159(3), 125.
• McGruder, C. D., L{'opez-Morales}, M., Espinoza, N., Rackham, B. V., Apai, D., Jord{'an}, A., Osip, D. J., Alam, M. K., Bixel, A., Fortney, J. J., Henry, G. W., Kirk, J., Lewis, N. K., Rodler, F., & Weaver, I. C. (2020). "ACCESS: Confirmation of No Potassium in the Atmosphere of WASP-31b". aj, 160(5), 230.
• Meusinger, H., Rudolf, C., Stecklum, B., Hoeft, M., Mauersberger, R., & Apai, D. (2020). "The galaxy population within the virial radius of the Perseus cluster". aap, 640, A30.
• Mulders, G. D., O'Brien, D. P., Ciesla, F. J., Apai, D., & Pascucci, I. (2020). "Earths in Other Solar Systems' N-body Simulations: The Role of Orbital Damping in Reproducing the Kepler Planetary Systems". apj, 897(1), 72.
• Radigan, J., Lowrance, P., Cowan, N. B., Miles-Perez, P. A., Metchev, S., Karalidi, T., Manjavacas, E., Burgasser, A. J., Schneider, G., Lew, B. W., Bedin, L. R., Apai, D., & Zhou, Y. (2020). Cloud Atlas: High-precision HST/WFC3/IR Time-Resolved Observations of Directly-Imaged Exoplanet HD 106906b. Astronomical Journal, 159, 140. doi:10.3847/1538-3881/ab6f65
• Tremblin, P., Phillips, M., Emery, A., Baraffe, I., Lew, B., Apai, D., Biller, B., & Bonnefoy, M. (2020). "Rotational spectral modulation of cloudless atmospheres for L/T brown dwarfs and extrasolar giant planets". aap, 643, A23.
• Wagner, K., Apai, D., Kasper, M., McClure, M., Robberto, M., & Currie, T. (2020). "Direct Imaging Discovery of a Young Brown Dwarf Companion to an A2V Star". apjl, 902(1), L6.
• Wagner, K., Stone, J., Dong, R., Ertel, S., Apai, D., Doelman, D., Bohn, A., Najita, J., Brittain, S., Kenworthy, M., Keppler, M., Webster, R., Mailhot, E., & Snik, F. (2020). "First Images of the Protoplanetary Disk around PDS 201". aj, 159(6), 252.
• Weaver, I. C., L{'opez-Morales}, M., Espinoza, N., Rackham, B. V., Osip, D. J., Apai, D., Jord{'an}, A., Bixel, A., Lewis, N. K., Alam, M. K., Kirk, J., McGruder, C., Rodler, F., & Fienco, J. (2020). "ACCESS: A Visual to Near-infrared Spectrum of the Hot Jupiter WASP-43b with Evidence of H$_{2$O, but No Evidence of Na or K}". aj, 159(1), 13.
• Yan, F., Espinoza, N., Molaverdikhani, K., Henning, T., Mancini, L., Mallonn, M., Rackham, B., Apai, D., Jord{'an}, A., Molli{`ere}, P., Chen, G., Carone, L., & Reiners, A. (2020). "LBT transmission spectroscopy of HAT-P-12b. Confirmation of a cloudy atmosphere with no significant alkali features". aap, 642, A98.
• Zhou, Y., Apai, D., Bedin, L. R., Lew, B. W., Schneider, G., Burgasser, A. J., Manjavacas, E., Karalidi, T., Metchev, S., Miles-P{'aez}, P. A., Cowan, N. B., Lowrance, P. J., & Radigan, J. (2020). "Cloud Atlas: High-precision HST/WFC3/IR Time-resolved Observations of Directly Imaged Exoplanet HD 106906b". aj, 159(4), 140.
• Zhou, Y., Bowler, B. P., Morley, C. V., Apai, D., Kataria, T., Bryan, M. L., & Benneke, B. (2020). "Spectral Variability of VHS J1256-1257b from 1 to 5 {ensuremath{mu}m}". aj, 160(2), 77.
• 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.
• Apai, D., Biller, B., Burgasser, A., Girard, J. H., Gizis, J. E., Karalidi, T., Kraus, A. L., Lew, B. W., Manjavacas, E., Marley, M., Miles-Paez, P. A., Morley, C. V., Radigan, J., Vos, J. M., & Zhou, Y. (2019). Mapping Ultracool Atmospheres: Time-domain Observations of Brown Dwarfs and Exoplanets. baas, 51(3), 204.
• Apai, D., Milster, T. D., Kim, D. W., Bixel, A., Schneider, G., Liang, R., & Arenberg, J. (2019). A Thousand Earths: A Very Large Aperture, Ultralight Space Telescope Array for Atmospheric Biosignature Surveys. aj, 158(2), 83.
• Bedin, L., Salaris, M., Anderson, J., Libralato, M., Apai, D., Nardiello, D., Rich, R., Bellini, A., Dieball, A., Bergeron, P., Burgasser, A., Milone, A., & Marino, A. (2019). The HST large programme on NGC 6752 - III. Detection of the peak of the white dwarf luminosity function. mnras, 488(3), 3857-3865.
• Bedin, L., Salaris, M., Rich, R., Richer, H., Anderson, J., Bettoni, D., Nardiello, D., Milone, A., Marino, A., Libralato, M., Bellini, A., Dieball, A., Bergeron, P., Burgasser, A., & Apai, D. (2019). The HST Large Programme on NGC 6752. I. Serendipitous discovery of a dwarf Galaxy in background. mnras, 484, L54-L58.
• Bixel, A., Rackham, B., Apai, D., Espinoza, N., L{'opez-Morales}, M., Osip, D., Jord{'an}, A., McGruder, C., & Weaver, I. (2019). ACCESS: Ground-based Optical Transmission Spectroscopy of the Hot Jupiter WASP-4b. aj, 157, 68.
• Boehle, A., Quanz, S., Lovis, C., S{'egransan}, D., Udry, S., & Apai, D. (2019). Combining high-contrast imaging and radial velocities to constrain the planetary architectures of nearby stars. aap, 630, A50.
• Burgasser, A., Apai, D., Bardalez, G. D., Blake, C., Gagne, J., Konopacky, Q., Martin, E., Metchev, S., Plavchan, P., Reiners, A., Schlawin, E., Sousa-Silva, C., & Vos, J. (2019). Astro2020 Science White Paper: High-Resolution Spectroscopic Surveys of Ultracool Dwarf Stars & Brown Dwarfs. arXiv e-prints, arXiv:1903.04664.
• Burgasser, A., Apai, D., Bardalez, G. D., Blake, C., Gagne, J., Konopacky, Q., Martin, E., Metchev, S., Reiners, A., Schlawin, E., Sousa-Silva, C., & Vos, J. (2019). High-Resolution Spectroscopic Surveys of Ultracool Dwarf Stars & Brown Dwarfs. baas, 51(3), 547.
• Checlair, J., Abbot, D. S., Webber, R. J., Feng, Y. K., Bean, J. L., Schwieterman, E. W., Stark, C. C., Robinson, T. D., Kempton, E., Alcabes, O. D., Apai, D., Arney, G., Cowan, N., Domagal-Goldman, S., Dong, C., Fleming, D. P., Fujii, Y., Graham, R., Guzewich, S. D., , Hasegawa, Y., et al. (2019). A Statistical Comparative Planetology Approach to Maximize the Scientific Return of Future Exoplanet Characterization Efforts. baas, 51(3), 404.
• Domagal-Goldman, S., Kiang, N. Y., Parenteau, N., Kamakolanu, U. G., Finster, K., Martin-Torres, J., Danielache, S. O., DasSarma, P., Tamura, M., Hori, Y., Rugheimer, S., Hartnett, H. E., Stockwell, B. R., Vazan, A., Hu, R., Cronin, L., M{'endez}, A., Smith, H. B., Demergasso, C., , Meadows, V. S., et al. (2019). Life Beyond the Solar System: Remotely Detectable Biosignatures. Astro2020: Decadal Survey on Astronomy and Astrophysics, 2020, 528.
• Espinoza, N., Rackham, B., Jord{'an}, A., Apai, D., L{'opez-Morales}, M., Osip, D., Grimm, S., Hoeijmakers, J., Wilson, P., Bixel, A., McGruder, C., Rodler, F., Weaver, I., Lewis, N., Fortney, J., & Fraine, J. (2019). ACCESS: a featureless optical transmission spectrum for WASP-19b from Magellan/IMACS. mnras, 482, 2065-2087.
• 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.
• Gibbs, A., Wagner, K., Apai, D., Mo{'or}, A., Currie, T., Bonnefoy, M., Langlois, M., & Lisse, C. (2019). VLT/SPHERE Multiwavelength High-contrast Imaging of the HD 115600 Debris Disk: New Constraints on the Dust Geometry and the Presence of Young Giant Planets. aj, 157, 39.
• 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. baas, 51(3), 414.
• Leggett, S., Apai, D., Burgasser, A., Cushing, M., Dupuy, T., Faherty, J., Gizis, J., Kirkpatrick, J. D., Marley, M., Morley, C., Schneider, A., & Sousa-Silva, C. (2019). Discovery of Cold Brown Dwarfs or Free-Floating Giant Planets Close to the Sun. baas, 51(3), 95.
• Leggett, S., Dupuy, T. J., Morley, C. V., Marley, M. S., Best, W. M., Liu, M. C., Apai, D., Casewell, S., Geballe, T., Gizis, J. E., Pineda, J. S., Rieke, M., & Wright, G. (2019). 3.8 ensuremath{mu}m Imaging of 400-600 K Brown Dwarfs and Orbital Constraints for WISEP J045853.90+643452.6AB. apj, 882(2), 117.
• Manjavacas, E., Apai, D., Lew, B. W., Zhou, Y., Schneider, G., Burgasser, A. J., Karalidi, T., Miles-P{'aez}, P. A., Lowrance, P. J., Cowan, N., Bedin, L. R., Marley, M. S., Metchev, S., & Radigan, J. (2019). Cloud Atlas: Rotational Spectral Modulations and Potential Sulfide Clouds in the Planetary-mass, Late T-type Companion Ross 458C. apjl, 875(2), L15.
• Manjavacas, E., Apai, D., Zhou, Y., Lew, B., Schneider, G., Metchev, S., Miles-P{'aez}, P., Radigan, J., Marley, M., Cowan, N., Karalidi, T., Burgasser, A., Bedin, L., Lowrance, P., & Kauffmann, P. (2019). Cloud Atlas: Hubble Space Telescope Near-infrared Spectral Library of Brown Dwarfs, Planetary-mass Companions, and Hot Jupiters. aj, 157, 101.
• Miles-P{'aez}, P. A., Metchev, S., Apai, D., Zhou, Y., Manjavacas, E., Karalidi, T., Lew, B. W., Burgasser, A. J., Bedin, L. R., Cowan, N., Lowrance, P. J., Marley, M. S., Radigan, J., & Schneider, G. (2019). Cloud Atlas: Variability in and out of the Water Band in the Planetary-mass HD 203030B Points to Cloud Sedimentation in Low-gravity L Dwarfs. apj, 883(2), 181.
• Milone, A., Marino, A., Bedin, L., Anderson, J., Apai, D., Bellini, A., Dieball, A., Salaris, M., Libralato, M., Nardiello, D., Bergeron, P., Burgasser, A., Rees, J., Rich, R., & Richer, H. (2019). The HST Large Programme on NGC 6752 - II. Multiple populations at the bottom of the main sequence probed in NIR. mnras, 484, 4046-4053.
• Mulders, G. D., Mordasini, C., Pascucci, I., Ciesla, F. J., Emsenhuber, A., & Apai, D. (2019). The Exoplanet Population Observation Simulator. II. Population Synthesis in the Era of Kepler. apj, 887(2), 157.
• Rackham, B., Apai, D., & Giampapa, M. (2019). The Transit Light Source Effect. II. The Impact of Stellar Heterogeneity on Transmission Spectra of Planets Orbiting Broadly Sun-like Stars. aj, 157, 96.
• Rackham, B., Pinhas, A., Apai, D., Haywood, R., Cegla, H., Espinoza, N., Teske, J., Gully-Santiago, M., Rau, G., Morris, B. M., Angerhausen, D., Barclay, T., Carone, L., Cauley, P. W., Wit, J., Domagal-Goldman, S., Dong, C., Dragomir, D., Giampapa, M. S., , Hasegawa, Y., et al. (2019). Constraining Stellar Photospheres as an Essential Step for Transmission Spectroscopy of Small Exoplanets. baas, 51(3), 328.
• Vos, J. M., Allers, K., Apai, D., Biller, B., Burgasser, A., Faherty, J., Gagn{'e}, J., Helling, C., Morley, C., Radigan, J., Showman, A., Tan, X., & Tremblin, P. (2019). Astro2020 White Paper: The L/T Transition. arXiv e-prints, arXiv:1903.06691.
• Vos, J., Allers, K., Apai, D., Biller, B., Burgasser, A. J., Faherty, J., Gagne, J., Helling, C., Morley, C., Radigan, J., Showman, A., Tan, X., & Tremblin, P. (2019). The L/T Transition. baas, 51(3), 253.
• Wagner, K., Apai, D., & Kratter, K. M. (2019). On the Mass Function, Multiplicity, and Origins of Wide-orbit Giant Planets. apj, 877(1), 46.
• Wagner, K., Stone, J. M., Spalding, E., Apai, D., Dong, R., Ertel, S., Leisenring, J., & Webster, R. (2019). Thermal Infrared Imaging of MWC 758 with the Large Binocular Telescope: Planetary-driven Spiral Arms?. apj, 882(1), 20.
• Zhou, Y., Apai, D., Lew, B. W., Schneider, G., Manjavacas, E., Bedin, L. R., Cowan, N. B., Marley, M. S., Radigan, J., Karalidi, T., Lowrance, P. J., Miles-P{'aez}, P. A., Metchev, S., & Burgasser, A. J. (2019). Erratum: Cloud Atlas: High-contrast Time-resolved Observations of Planetary-mass Companions. aj, 158(1), 52.
• Zhou, Y., Apai, D., Lew, B., Schneider, G., Manjavacas, E., Bedin, L., Cowan, N., Marley, M., Radigan, J., Karalidi, T., Lowrance, P., Miles-P{'aez}, P., Metchev, S., & Burgasser, A. (2019). Cloud Atlas: High-contrast Time-resolved Observations of Planetary-mass Companions. aj, 157, 128.
• Apai, D., Ciesla, F., Mulders, G., Pascucci, I., Barry, R., Pontoppidan, K., Bergin, E., Bixel, A., Brittain, S., Domagal-Goldman, S., Hasegawa, Y., Jang-Condell, H. .., Malhotra, R., Meyer, M., Youdin, A., Teske, J., & Turner, N. (2018). A comprehensive understanding of planet formation is required for assessing planetary habitability and for the search for life. arXiv e-prints.
• Apai, D., Rackham, B., Giampapa, M., Angerhausen, D., Teske, J., Barstow, J., Carone, L., Cegla, H., Domagal-Goldman, S., Espinoza, N., Giles, H., Gully-Santiago, M. .., Haywood, R., Hu, R., Jordan, A., Kreidberg, L., Line, M., Llama, J., L{'opez-Morales}, M., , Marley, M., et al. (2018). Understanding Stellar Contamination in Exoplanet Transmission Spectra as an Essential Step in Small Planet Characterization. arXiv e-prints.
• Bellini, A., Libralato, M., Bedin, L., Milone, A., Marel, R., Anderson, J., Apai, D., Burgasser, A., Marino, A., & Rees, J. (2018). "The HST Large Programme on {$omega$ Centauri. II. Internal Kinematics}". apj, 853, 86.
• Burnam-Fink, M. .., Desch, S., Scalice, D., Davis, H., Huff, C., & Apai, D. (2018). Impact of the Arizona NExSS Winter School on Astrobiology Knowledge and Attitudes. Astrobiology, 18, 365-375.
• Libralato, M., Bellini, A., Bedin, L., Moreno, D. E., Fern{'andez-Trincado}, J., Pichardo, B., Marel, R., Anderson, J., Apai, D., Burgasser, A., Fabiola Marino, A., Milone, A., Rees, J., & Watkins, L. (2018). "The HST Large Programme on {$omega$ Centauri. III. Absolute Proper Motion}". apj, 854, 45.
• Long, F., Herczeg, G., Pascucci, I., Apai, D., Henning, T., Manara, C., Mulders, G., Sz{H, u. L., & Hendler, N. (2018). An ALMA Survey of Faint Disks in the Chamaeleon I Star-forming Region: Why Are Some Class II Disks so Faint?. apj, 863, 61.
• Manjavacas, E., Apai, D., Zhou, Y., Karalidi, T., Lew, B. W., Schneider, G., Cowan, N., Metchev, S., Miles-Paez, P. A., Burgasser, A. J., Radigan, J., Bedin, L. R., Lowrance, P. J., & Marley, M. J. (2018). Cloud Atlas: Discovery of Rotational Spectral Modulations in a Low-mass, L-type Brown Dwarf Companion to a Star. Astronomical Journal, 155(1), 11 - 20. doi:10.3847/1538-3881/aa984f
• Mulders, G., Pascucci, I., Apai, D., & Ciesla, F. (2018). The Exoplanet Population Observation Simulator. I. The Inner Edges of Planetary Systems. aj, 156, 24.
• Pinhas, A., Rackham, B., Madhusudhan, N., & Apai, D. (2018). Retrieval of planetary and stellar properties in transmission spectroscopy with AURA. mnras, 480, 5314-5331.
• Rackham, B., Apai, D., & Giampapa, M. (2018). "The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets". apj, 853, 122.
• Stone, J., Skemer, A., Hinz, P., Bonavita, M., Kratter, K., Maire, A., Defrere, D., Bailey, V., Spalding, E., Leisenring, J., Desidera, S., Bonnefoy, M., Biller, B., Woodward, C., Henning, T., Skrutskie, M., Eisner, J., Crepp, J., Patience, J., , Weigelt, G., et al. (2018). The LEECH Exoplanet Imaging Survey: Limits on Planet Occurrence Rates under Conservative Assumptions. aj, 156, 286.
• Wagner, K., Dong, R., Sheehan, P., Apai, D., Kasper, M., McClure, M., Morzinski, K., Close, L., Males, J., Hinz, P., Quanz, S., & Fung, J. (2018). "The Orbit of the Companion to HD 100453A: Binary-driven Spiral Arms in a Protoplanetary Disk". apj, 854, 130.
• Wagner, K., Follete, K., Close, L., Apai, D., Gibbs, A., Keppler, M., M{"uller}, A., Henning, T., Kasper, M., Wu, Y., Long, J., Males, J., Morzinski, K., & McClure, M. (2018). Magellan Adaptive Optics Imaging of PDS 70: Measuring the Mass Accretion Rate of a Young Giant Planet within a Gapped Disk. apjl, 863, L8.
• Zhang, Z., Zhou, Y., Rackham, B., & Apai, D. (2018). "The Near-Infrared Transmission Spectra of TRAPPIST-1 Planets b, c, d, e, f, and g and Stellar Contamination in Multi-Epoch Transit Spectra". ArXiv e-prints.
• Zhou, Y., Apai, D., Metchev, S., Lew, B., Schneider, G., Marley, M., Karalidi, T., Manjavacas, E., Bedin, L., Cowan, N., Miles-P{'aez}, P., Lowrance, P., Radigan, J., & Burgasser, A. (2018). "Cloud Atlas: Rotational Modulations in the L/T Transition Brown Dwarf Companion HN Peg B". aj, 155, 132.
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• Apai, D., Cowan, N., Kopparapu, R., Kasper, M., Hu, R., Morley, C., Fujii, Y., Kane, S., Maley, M., Genio, A., Karalidi, T., Komacek, T., Mamajek, E., Mandell, A., Domagal-Goldman, S. .., Barman, T., Boss, A., Breckinridge, J., Crossfield, I., , Danchi, W., et al. (2017). "Exploring Other Worlds: Science Questions for Future Direct Imaging Missions (EXOPAG SAG15 Report)". ArXiv e-prints.
• Apai, D., Karalidi, T., Marley, M., Yang, H., Flateau, D., Metchev, S., Cowan, N., Buenzli, E., Burgasser, A., Radigan, J., Artigau, E., & Lowrance, P. (2017). "Zones, spots, and planetary-scale waves beating in brown dwarf atmospheres". Science, 357, 683-687.
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• Rackham, B., Espinoza, N., Apai, D., L{'opez-Morales}, M., Jord{'an}, A., Osip, D., Lewis, N., Rodler, F., Fraine, J., Morley, C., & Fortney, J. (2017). "ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a Heterogeneous Stellar Photosphere". apj, 834, 151.
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• Smart, R., Apai, D., Kirkpatrick, J., Leggett, S., Marocco, F., Morrison, J., Jones, H., Pinfield, D., Tremblin, P., & Amundsen, D. (2017). "Parallaxes and infrared photometry of three Y0 dwarfs". mnras, 468, 3764-3774.
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• Zhou, Y., Apai, D., Lew, B., & Schneider, G. (2017). "A Physical Model-based Correction for Charge Traps in the Hubble Space Telescope{rsquos Wide Field Camera 3 Near-IR Detector and Its Applications to Transiting Exoplanets and Brown Dwarfs}". aj, 153, 243.
• Zhou, Y., Schneider, G., Apai, D., & Low, B. W. (2016). A Physically Motivated Model of Charge Traps in the Hubble Space Telescope's Wide Field Camera 3 Near-IR Detector and its Applications to Transiting Exoplanets and Brown Dwarfs. Astrophysical Journal, 15pp.
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• Hornbeck, J., Swearingen, J., Grady, C., Williger, G., Brown, A., Sitko, M., Wisniewski, J., Perrin, M., Lauroesch, J., Schneider, G., Apai, D., Brittain, S., Brown, J., Champney, E., Hamaguchi, K., Henning, T., Lynch, D., Petre, R., Russell, R., , Walter, F., et al. (2016). "Panchromatic Imaging of a Transitional Disk: The Disk of GM Aur in Optical and FUV Scattered Light". apj, 829, 65.
• Karalidi, T., Apai, D., Marley, M. S., & Buenzli, E. (2016). MAPS OF EVOLVING CLOUD STRUCTURES IN LUHMAN 16AB FROM HST TIME-RESOLVED SPECTROSCOPY.. Astrophysical Journal, 224, 22.
• 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
• Lew, B. W., Apai, D., Zhou, Y., Schneider, G., Burgasser, A. J., Karalidi, T., Yand, H., Marley, M. S., Cowan, N. B., Bedin, L. R., Metchev, S. A., Radigan, J., & Lowrance, P. J. (2016). Cloud Atlas: Discovery of Patchy Clouds and High-amplitude Rotational Modulations in a Young, Extremely Red L-type Brown Dwarf. Astrophysical Journal, 32L - 38L. doi:10.3847/2041-8205/829/2/L32
• Mulders, G., Pascucci, I., Apai, D., Frasca, A., & Molenda-{.Zakowicz}, J. (2016). "A Super-solar Metallicity for Stars with Hot Rocky Exoplanets". aj, 152, 187.
• Pascucci, I., Testi, L., Herczeg, G., Long, F., Manara, C., Hendler, N., Mulders, G., Krijt, S., Ciesla, F., Henning, T., Mohanty, S., Drabek-Maunder, E. .., Apai, D., Sz{H, u. L., Sacco, G., & Olofsson, J. (2016). "A Steeper than Linear Disk Mass-Stellar Mass Scaling Relation". apj, 831, 125.
• Wagner, K., Apai, D., Markus, K., Kratter, K., McClure, M., Robberto, M., & Beuzit, J. (2016). Direct imaging discovery of a Jovian exoplanet within a triple-star system. Science, 673, 353.
• Yang, H., Apai, D., Marley, M. S., Karalidi, T., Flateau, D., Metchev, S., & Buenzli, E. (2016). EXTRASOLAR STORMS: PRESSURE-DEPENDENT CHANGES IN LIGHT CURVE PHASE IN BROWN DWARFS FROM SIMULTANEOUS HUBBLE AND SPITZER OBSERVATIONS. Astrophysical Journal, 826, 8.
• Zhou, Y., Showman, A. P., Marley, M. S., Apai, D., Schneider, G. H., Schneider, G. H., Marley, M. S., Apai, D., Zhou, Y., & Showman, A. P. (2016). Discovery of Rotational Modulations in the Planetary-Mass Companion 2M1207b: Intermediate Rotation Period and Heterogeneous Clouds in a Low Gravity Atmosphere. Astrophysical Journal, 818, 176.
• {Kun}, M., {Wolf-Chase}, G., {Mo{'o}r}, A., {Apai}, D., {Balog}, Z., {O'Linger-Luscusk}, J., , G. (2016). The young stellar population of Lynds 1340. An infrared view. Astrophysical Journal Supplement, 224, 22.
• {Skemer}, A., {Morley}, C., {Zimmerman}, N., {Skrutskie}, M., {Leisenring}, J., {Buenzli}, E., {Bonnefoy}, M., {Bailey}, V., {Hinz}, P., {Defr{'e}re}, D., {Esposito}, S., {Apai}, D., {Biller}, B., {Brandner}, W., {Close}, L., {Crepp}, J., {De Rosa}, R., {Desidera}, S., {Eisner}, J., , {Fortney}, J., et al. (2016). "{The LEECH Exoplanet Imaging Survey: Characterization of the Coldest Directly Imaged Exoplanet, GJ 504 b, and Evidence for Superstellar Metallicity}". apj, 817, 166.
• {Zurlo}, A., {Vigan}, A., {Galicher}, R., {Maire}, A., {Mesa}, D., {Gratton}, R., {Chauvin}, G., {Kasper}, M., {Moutou}, C., {Bonnefoy}, M., {Desidera}, S., {Abe}, L., {Apai}, D., {Baruffolo}, A., {Baudoz}, P., {Baudrand}, J., {Beuzit}, J., {Blancard}, P., {Boccaletti}, A., , {Cantalloube}, F., et al. (2016). "{First light of the VLT planet finder SPHERE. III. New spectrophotometry and astrometry of the HR 8799 exoplanetary system}". aap, 587, A57.
• Apai, D., Schneider, G., Grady, C. A., Wyatt, M. C., Lagrange, A., Kuchner, M. J., Stark, C. C., & Lubow, S. H. (2015). The Inner Disk Structure, Disk-Planet Interactions, and Temporal Evolution in the β Pictoris System: A Two-epoch HST/STIS Coronagraphic Study. Astrophysical Journal, 800(2), 136 - 157. doi:10.1088/0004-637X/800/2/136
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• Buenzli, E., Saumon, D., Marley, M. S., Apai, D., Radigan, J., Bedin, L. R., Reid, I. N., & Morley, C. V. (2015). Cloud Structure of the Nearest Brown Dwarfs: Spectroscopic Variability of Luhman 16AB from the Hubble Space Telescope. apj, 798, 127.
• Ciesla, F. J., Mulders, G. D., Pascucci, I., & Apai, D. (2015). Volatile Delivery to Planets from Water-rich Planetesimals around Low Mass Stars. Astrophysical Journal.
• Karalidi, T., Apai, D., Schneider, G., Hanson, J. R., & Pasachoff, J. M. (2015). AEOLUS: A Markov Chain Monte Carlo Code for Mapping Ultracool Atmospheres. An Application on Jupiter and Brown Dwarf HST Light Curves. Astrophysical Journal, 814(1), 65 - 81. doi:10.1088/0004-637X/814/1/65
• Karalidi, T., Yang, H., Apai, D., Saumon, D., Marley, M. S., Morley, C. V., Buenzli, E., Artigau, '., Radigan, J., Metchev, S., Burgasser, A. J., Mohanty, S., Lowrance, P. J., Showman, A. P., Flateau, D., & Heinze, A. N. (2015). HST Rotational Spectral Mapping of Two L-type Brown Dwarfs: Variability in and out of Water Bands indicates High-altitude Haze Layers. apjl, 798, L13.
• Metchev, S. A., Heinze, A., Apai, D., Flateau, D., Radigan, J., Burgasser, A., Marley, M. S., Artigau, '., Plavchan, P., & Goldman, B. (2015). Weather on Other Worlds. II. Survey Results: Spots are Ubiquitous on L and T Dwarfs. apj, 799, 154.
• Mo'or, A., K'osp'al, '., 'Abrah'am, P., Apai, D., Balog, Z., Grady, C., Henning, T., Juh'asz, A., Kiss, C., Krivov, A. V., Pawellek, N., & Szab'o, G. M. (2015). Stirring in massive, young debris discs from spatially resolved Herschel images. mnras, 447, 577-597.
• Mulders, G. D., Pascucci, I., & Apai, D. (2015). A Stellar-mass-dependent Drop in Planet Occurrence Rates. apj, 798, 112.
• Mulders, G., Ciesla, F., Pascucci, I., & Apai, D. (2015). The Water Content of Exo-earths in the Habitable Zone around Low-mass Stars. IAU General Assembly, 22, 2256008.
• Mulders, G., Pascucci, I., & Apai, D. (2015). "{Small, Numerous and Close-in: The Population of Planets around Low-mass Stars.}". IAU General Assembly, 22, 2256025.
• {Buenzli}, E., {Marley}, M., {Apai}, D., {Saumon}, D., {Biller}, B., {Crossfield}, I., , J. (2015). "{Cloud Structure of the Nearest Brown Dwarfs. II. High-amplitude Variability for Luhman 16 A and B in and out of the 0.99 {$mu$}m FeH feature}". apj, 812, 163.
• {Gaudi}, B., {Agol}, E., {Apai}, D., {Bendek}, E., {Boss}, A., {Breckinridge}, J., {Ciardi}, D., {Cowan}, N., {Danchi}, W., {Domagal-Goldman}, S., {Fortney}, J., {Greene}, T., {Kaltenegger}, L., {Kasting}, J., {Leisawitz}, D., {Leger}, A., {Lille}, C., {Lisman}, D., {Lo}, A., , {Malbet}, F., et al. (2015). Exoplanet Exploration Program Analysis Group (ExoPAG) Report to Paul Hertz Regarding Large Mission Concepts to Study for the 2020 Decadal Survey. ArXiv e-prints.
• {Kasper}, M., {Apai}, D., {Wagner}, K., , M. (2015). "{Discovery of an Edge-on Debris Disk with a Dust Ring and an Outer Disk Wing-tilt Asymmetry}". apjl, 812, L33.
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• {Wagner}, K., {Apai}, D., {Kasper}, M., , M. (2015). "{Discovery of a Two-armed Spiral Structure in the Gapped Disk around Herbig Ae Star HD 100453}". apjl, 813, L2.
• {Zurlo}, A., {Vigan}, A., {Galicher}, R., {Maire}, A., {Mesa}, D., {Gratton}, R., {Chauvin}, G., {Kasper}, M., {Moutou}, C., {Bonnefoy}, M., {Desidera}, S., {Abe}, L., {Apai}, D., {Baruffolo}, A., {Baudoz}, P., {Baudrand}, J., {Beuzit}, J., {Blancard}, P., {Boccaletti}, A., , {Cantalloube}, F., et al. (2015). VizieR Online Data Catalog: HR 8799e and HR 8799d spectra (Zurlo+, 2016). VizieR Online Data Catalog, 358.
• Bonnefoy, M., Boccaletti, A., Lagrange, A., Allard, F., Mordasini, C., Beust, H., Chauvin, G., H., J., Homeier, D., Apai, D., Lacour, S., Rouan, D., Rameau, J., & Klahr, H. (2014). Properties of the young gas giant planet β Pictoris b. Proceedings of the International Astronomical Union, 8(S299), 241-246.
  More info

  Abstract: The young (12+8-4 Myr) and nearby (19.44±0.05 pc) star β Pictoris is considered one of the best laboratories for the study of early phases of planetary systems formation since the identification of an extended debris disk surrounding the star in 1984. In 2009, we imaged at 3.8 μm with NaCo at VLT a gas giant planet around β Pictoris, roughly along the disk mid-plane, with a semi-major axis between 8 and 14 AU. We present here the first images of the planet in the J (1.265 μm), H (1.66 μm), and M' (4.78 μm) bands obtained between 2011 and 2012. We used these data to build the 1-5 μm spectral energy distribution (SED) of the companion, and to consolidate previous semi-major axis (8-10 AU) estimates. We compared the SED to seven atmospheric models to derive Teff = 1700 ± 100 K. We used the temperature and the luminosity of β Pictoris b to estimate new masses for the companion. We compared these masses to independent constraints set by the orbital parameters and the radial velocities and use them to discuss the formation history of the object. Copyright © 2013, International Astronomical Union.
• Buenzli, E., Apai, D., Radigan, J., Reid, I. N., & Flateau, D. (2014). Brown dwarf photospheres are patchy: A hubble space telescope near-infrared spectroscopic survey finds frequent low-level variability. Astrophysical Journal, 782(2).
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  Abstract: Condensate clouds strongly impact the spectra of brown dwarfs and exoplanets. Recent discoveries of variable L/T transition dwarfs argued for patchy clouds in at least some ultracool atmospheres. This study aims to measure the frequency and level of spectral variability in brown dwarfs and to search for correlations with spectral type. We used Hubble Space Telescope/Wide Field Camera 3 to obtain spectroscopic time series for 22 brown dwarfs of spectral types ranging from L5 to T6 at 1.1-1.7 μm for 40 minutes per object. Using Bayesian analysis, we find six brown dwarfs with confident (p > 95%) variability in the relative flux in at least one wavelength region at sub-percent precision, and five brown dwarfs with tentative (p > 68%) variability. We derive a minimum variability fraction over all covered spectral types. The fraction of variables is equal within errors for mid-L, late-L, and mid-T spectral types; for early-T dwarfs we do not find any confident variable but the sample is too small to derive meaningful limits. For some objects, the variability occurs primarily in the flux peak in the J or H band, others are variable throughout the spectrum or only in specific absorption regions. Four sources may have broadband peak-to-peak amplitudes exceeding 1%. Our measurements are not sensitive to very long periods, inclinations near pole-on and rotationally symmetric heterogeneity. The detection statistics are consistent with most brown dwarf photospheres being patchy. While multiple-percent near-infrared variability may be rare and confined to the L/T transition, low-level heterogeneities are a frequent characteristic of brown dwarf atmospheres. © 2014. The American Astronomical Society. All rights reserved..
• Close, L. M., Follette, K. B., Males, J. R., Puglisi, A., Xompero, M., Apai, D., Najita, J., Weinberger, A. J., Morzinski, K., Rodigas, T. J., Hinz, P., Bailey, V., & Briguglio, R. (2014). Discovery of H$alpha$ Emission from the Close Companion inside the Gap of Transitional Disk HD 142527. apjl, 781, L30.
• Kun, M., Apai, D., O'Linger-Luscusk, J., Mo'or, A., Stecklum, B., Szegedi-Elek, E., & Wolf-Chase, G. (2014). New Candidate Eruptive Young Stars in Lynds 1340. apjl, 795, L26.
• Todorov, K. O., Luhman, K. L., Konopacky, Q. M., McLeod, K. K., Apai, D., Ghez, A. M., Pascucci, I., & Robberto, M. (2014). A Search for Companions to Brown Dwarfs in the Taurus and Chamaeleon Star-Forming Regions. apj, 788, 40.
• Apai, D. (2013). Protoplanetary disks and planet formation around brown dwarfs and very low-mass stars. Astronomische Nachrichten, 334(1-2), 57-62.
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  Abstract: Brown dwarfs and very low-mass stars are very common in the Galaxy, yet we know little about the planetary systems they may host. Here we review observational evidence emerging from comparative studies of disks around brown dwarfs and sun-like stars. These studies show that very young brown dwarfs and very low mass stars have disks as frequently as sun-like stars do, arguing for the same formation processes. There are indications, but no conclusive evidence yet, for a longer disk lifetime around the lowest-mass stars and brown dwarfs. At the same time, evidence for faster dust processing and more strongly reduced disk scale heights is found, demonstrating that the first steps of planet formation also take place around brown dwarfs. With increasingly sensitive infrared instruments a new window is opening on gas-phase chemistry in these disks and the first surveys indicate a different gas-phase chemistry and, perhaps, a suppressed nitrogen chemistry. Sub-millimeter surveys reveal disk masses of a few Jupiter mass, which core accretion models show is enough to form few Earth-mass and smaller planets, but not gas giant planets. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
• Apai, D., Radigan, J., Buenzli, E., Burrows, A., Reid, I. N., & Jayawardhana, R. (2013). HST spectral mapping of L/T transition brown dwarfs reveals cloud thickness variations. Astrophysical Journal, 768(2).
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  Abstract: Most directly imaged giant exoplanets are fainter than brown dwarfs with similar spectra. To explain their relative underluminosity, unusually cloudy atmospheres have been proposed. However, with multiple parameters varying between any two objects, it remained difficult to observationally test this idea. We present a new method, sensitive time-resolved Hubble Space Telescope near-infrared spectroscopy, to study two rotating L/T transition brown dwarfs (2M2139 and SIMP0136). The observations provide spatially and spectrally resolved mapping of the cloud decks of the brown dwarfs. The data allow the study of cloud structure variations while other parameters are unchanged. We find that both brown dwarfs display variations of identical nature: J- and H-band brightness variations with minimal color and spectral changes. Our light curve models show that even the simplest surface brightness distributions require at least three elliptical spots. We show that for each source the spectral changes can be reproduced with a linear combination of only two different spectra, i.e., the entire surface is covered by two distinct types of regions. Modeling the color changes and spectral variations together reveal patchy cloud covers consisting of a spatially heterogeneous mix of low-brightness, low-temperature thick clouds and brighter, thin, and warm clouds. We show that the same thick cloud patches seen in our varying brown dwarf targets, if extended to the entire photosphere, predict near-infrared colors/magnitudes matching the range occupied by the directly imaged exoplanets that are cooler and less luminous than brown dwarfs with similar spectral types. This supports the models in which thick clouds are responsible for the near-infrared properties of these "underluminous" exoplanets. © 2013. The American Astronomical Society. All rights reserved.
• Bonnefoy, M., Boccaletti, A., Lagrange, A. -., Allard, F., Mordasini, C., Beust, H., Chauvin, G., Girard, J. H., Homeier, D., Apai, D., Lacour, S., & Rouan, D. (2013). The near-infrared spectral energy distribution of β Pictoris b. Astronomy and Astrophysics, 555.
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  Abstract: Context. A gas giant planet has previously been directly seen orbiting at 8-10 AU within the debris disk of the ∼12 Myr old star Pictoris. The β Pictoris system offers the rare opportunity of both studying the physical and atmospheric properties of an exoplanet placed on a wide orbit and establishing its formation scenario. Aims. We aim to build the 1-5 μm spectral energy distribution of the planet for the first time. Our goal is to provide secure and accurate constraints on its physical and chemical properties. Methods. We obtained J (1.265 μm), H (1.66 μm), and M0 (4.78 μm) band angular differential imaging of the system between 2011 and 2012.We used Markov chain Monte Carlo simulations of the astrometric data to revise constraints on the orbital parameters of the planet. Photometric measurements were compared to those of ultra-cool dwarfs and young companions. They were combined with existing photometry (2.18, 3.80, and 4.05 μm) and compared to predictions from 7 PHOENIX-based atmospheric models in order to derive the atmospheric parameters (Teff, log g) of β Pictoris b. Predicted properties from ("hot-start", "cold-start", and "warm start") evolutionary models were compared to independent constraints on the mass of β Pictoris b. We used planet-population synthesis models following the core-accretion paradigm to discuss the planet's possible origin. Results. We detect the planetary companion in our four-epoch observations. We estimate J = 14:0 ± 0:3, H = 13:5 ± 0:2, and M0 = 11:0 ± 0:3 mag. Our new astrometry consolidates previous semi-major axis (8-10 AU) and excentricity (e 0:15) estimates of the planet. The location of β Pictoris b in color-magnitude diagrams suggests it has spectroscopic properties similar to L0-L4 dwarfs. This enables one to derive Log10 (L=L ·) =-3.87±0.08 for the companion. The analysis with atmospheric models reveals that the planet has a dusty atmosphere with Teff = 1700 ± 100 K and log q =4.0 ± 0.5. "Hot-start" evolutionary models give a new mass of 10+3-2 Mjup from Teff and 9+3-2 Mjup from luminosity. Predictions of "Cold-start" models are still inconsistent with independent constraints on the planet mass. "Warm-start" models constrains the mass to M≥ 6 Mjup and the initial entropies to value (Sinit≥9.3k b/baryon) midway between those considered for cold/hot-start models, but probably closer to those of hot-start models. © 2013 ESO.
• Gucsik, A., Endo, T., Nishido, H., Ninagawa, K., Kayama, M., Bérczi, S., Nagy, S., Ábrahám, P., Kimura, Y., Miura, H., Gyollai, I., Simonia, I., Rózsa, P., Posta, J., Apai, D., Mihályi, K., Nagy, M., & Ott, U. (2013). Cathodoluminescence microscopy and spectroscopy of forsterite from Kaba meteorite: An application to the study of hydrothermal alteration of parent body. Meteoritics and Planetary Science, 48(12), 2577-2596.
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  Abstract: Highly forsteritic olivine (Fo: 99.2-99.7) in the Kaba meteorite emits bright cathodoluminescence (CL). CL spectra of red luminescent forsterite grains have two broad emission bands at approximately 630 nm (impurity center of divalent Mn ions) in the red region and above 700 nm (trivalent Cr ions) in the red-IR region. The cores of the grains show CL blue luminescence giving a characteristic broad band emission at 400 nm, also associated with minor red emissions related to Mn and Cr ions. CL color variation of Kaba forsterite is attributed to structural defects. Electron probe microanalyzer (EPMA) analysis shows concentrations of Ca, Al, and Ti in the center of the forsterite grain. The migration of diffusible ions of Mn, Cr, and Fe to the rim of the Kaba meteoritic forsterite was controlled by the hydrothermal alteration at relatively low temperature (estimated at about 250 °C), while Ca and Al ions might still lie in the core. A very unusual phase of FeO (wüstite) was also observed, which may be a terrestrial alteration product of FeNi-metal. © The Meteoritical Society, 2013.
• Heinze, A. N., Metchev, S., Apai, D., Flateau, D., Kurtev, R., Marley, M., Radigan, J., Burgasser, A. J., Artigau, É., & Plavchan, P. (2013). Weather on other worlds. I. Detection of periodic variability in the L3 dwarf DENIS-P J1058.7-1548 with precise multi-wavelength photometry. Astrophysical Journal, 767(2).
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  Abstract: Photometric monitoring from warm Spitzer reveals that the L3 dwarf DENIS-P J1058.7-1548 varies sinusoidally in brightness with a period of hr and an amplitude of 0.388% ± 0.043% (peak-to-valley) in the 3.6 μm band, confirming the reality of a 4.31 ± 0.31 hr periodicity detected in J-band photometry from the SOAR telescope. The J-band variations are a factor of 2.17 ± 0.35 larger in amplitude than those at 3.6 μm, while 4.5 μm Spitzer observations yield a 4.5 μm/3.6 μm amplitude ratio of only 0.23 ± 0.15, consistent with zero 4.5 μm variability. This wide range in amplitudes indicates rotationally modulated variability due to magnetic phenomena and/or inhomogeneous cloud cover. Weak Hα emission indicates some magnetic activity, but it is difficult to explain the observed amplitudes by magnetic phenomena unless they are combined with cloud inhomogeneities (which might have a magnetic cause). However, inhomogeneous cloud cover alone can explain all our observations, and our data align with theory in requiring that the regions with the thickest clouds also have the lowest effective temperature. Combined with published vsin (i) results, our rotation period yields a 95% confidence lower limit of R * ≥ 0.111 R, suggesting upper limits of 320 Myr and 0.055 M on the age and mass. These limits should be regarded cautiously because of 3σ inconsistencies with other data; however, a lower limit of 45° on the inclination is more secure. DENIS-P J1058.7-1548 is only the first of nearly two dozen low-amplitude variables discovered and analyzed by the Weather on Other Worlds project. © 2013. The American Astronomical Society. All rights reserved..
• Kostov, V., & Apai, D. (2013). Mapping directly imaged giant exoplanets. Astrophysical Journal, 762(1).
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  Abstract: With the increasing number of directly imaged giant exoplanets, the current atmosphere models are often not capable of fully explaining the spectra and luminosity of the sources. A particularly challenging component of the atmosphere models is the formation and properties of condensate cloud layers, which fundamentally impact the energetics, opacity, and evolution of the planets. Here we present a suite of techniques that can be used to estimate the level of rotational modulations these planets may show. We propose that the time-resolved observations of such periodic photometric and spectroscopic variations of extrasolar planets due to their rotation can be used as a powerful tool to probe the heterogeneity of their optical surfaces. In this paper, we develop simulations to explore the capabilities of current and next-generation ground- and space-based instruments for this technique. We address and discuss the following questions: (1) what planet properties can be deduced from the light curve and/or spectra, and in particular can we determine rotation periods, spot coverage, spot colors, and spot spectra?; (2) what is the optimal configuration of instrument/wavelength/temporal sampling required for these measurements?; and (3) can principal component analysis be used to invert the light curve and deduce the surface map of the planet? Our simulations describe the expected spectral differences between homogeneous (clear or cloudy) and patchy atmospheres, outline the significance of the dominant absorption features of H2O, CH4, and CO, and provide a method to distinguish these two types of atmospheres. Assuming surfaces with and without clouds for most currently imaged planets the current models predict the largest variations in the J band. Simulated photometry from current and future instruments is used to estimate the level of detectable photometric variations. We conclude that future instruments will be able to recover not only the rotation periods, cloud cover, cloud colors, and spectra but even cloud evolution. We also show that a longitudinal map of the planet's atmosphere can be deduced from its disk-integrated light curves. © 2013. The American Astronomical Society. All rights reserved.
• Metchev, S., Apai, D., Radigan, J., Artigau, É., Heinze, A., Helling, C., Homeier, D., Littlefair, S., Morley, C., Skemer, A., & Stark, C. (2013). Clouds brown dwarfs and giant planets. Astronomische Nachrichten, 334(1-2), 40-43.
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  Abstract: A growing body of observational and theoretical evidence points toward the importance of clouds the atmospheres of ultra-cool brown dwarfs and giant planets. Empirically, the presence of clouds is inferred from the red, likely dusty atmospheres of young substellar objects, and from detections of periodic variability a fraction of brown dwarfs - as expected from rotation and a patchy cloud cover. Theoretical models have progressed alongside by including ever more comprehensive atomic and molecular opacity tables, incorporating the treatment of non-equilibrium chemistry and clouds through vertical mixing and grasize/sedimentation parameters, and employing 3-D hydrodynamical simulations. In this proceeding we summarize the key issues raised during the first gathering of observers and theorists to discuss clouds and atmospheric circulation non-irradiated ultra-cool dwarfs and giant planets. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
• Rogers, J., López-Morales, M., Apai, D., & Adams, E. (2013). Benchmark tests for Markov Chain Monte Carlo fitting of exoplanet eclipse observations. Astrophysical Journal, 767(1).
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  Abstract: Ground-based observations of exoplanet eclipses provide important clues to the planets' atmospheric physics, yet systematics in light curve analyses are not fully understood. It is unknown if measurements suggesting near-infrared flux densities brighter than models predict are real, or artifacts of the analysis processes. We created a large suite of model light curves, using both synthetic and real noise, and tested the common process of light curve modeling and parameter optimization with a Markov Chain Monte Carlo algorithm. With synthetic white noise models, we find that input eclipse signals are generally recovered within 10% accuracy for eclipse depths greater than the noise amplitude, and to smaller depths for higher sampling rates and longer baselines. Red noise models see greater discrepancies between input and measured eclipse signals, often biased in one direction. Finally, we find that in real data, systematic biases result even with a complex model to account for trends, and significant false eclipse signals may appear in a non-Gaussian distribution. To quantify the bias and validate an eclipse measurement, we compare both the planet-hosting star and several of its neighbors to a separately chosen control sample of field stars. Re-examining the Rogers et al. Ks-band measurement of CoRoT-1b finds an eclipse 3190-440+370 ppm deep centered at φme = 0.50418-0.00203+0.00197. Finally, we provide and recommend the use of selected data sets we generated as a benchmark test for eclipse modeling and analysis routines, and propose criteria to verify eclipse detections. © 2013. The American Astronomical Society. All rights reserved.
• Chauvin, G., Lagrange, A. -., Beust, H., Bonnefoy, M., Boccaletti, A., Apai, D., Allard, F., Ehrenreich, D., Girard, J. H., Mouillet, D., & Rouan, D. (2012). Orbital characterization of the β Pictoris b giant planet. Astronomy and Astrophysics, 542.
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  Abstract: Context. In June 2010, we confirmed the existence of a giant planet in the disk of the young star βPictoris located between 8 AU and 15 AU from the star. This young planet offers the rare opportunity to monitor a large fraction of the orbit using the imaging technique over a reasonably short timescale. It also offers the opportunity to study its atmospheric properties using spectroscopy and multi-band photometry, and possibly derive its dynamical mass by combining imaging with radial velocity data to set tight constraints on giant planet formation theories. Aims. We aim to measure the evolution of the planet's position relative to the star βPictoris to determine the planetary orbital properties. Our ultimate goal is to relate both the planetary orbital configuration and physical properties to either the disk structure or the cometary activity observed for decades in the βPictoris system. Methods. Using the NAOS-CONICA adaptive-optics instrument (NACO) at the Very Large Telescope (VLT), we obtained repeated follow-up images of the βPictoris system in the K s and L′ filters at four new epochs in 2010 and 2011. Complementing these data with previous measurements, we conduct a homogeneous analysis, which covers more than eight yrs, to accurately monitor the βPictoris b position relative to the star. We then carefully consider the various sources of uncertainties that may affect the orbital parameter determination. Results. On the basis of the evolution of the planet's relative position with time, we derive the best-fit orbital solutions for our measurements using two fitting methods, a least squares Levenberg-Marquardt algorithm and a Markov-chain Monte Carlo approach. More reliable results are found with the second approach as our measurements do not cover the complete planetary orbit, and are biased toward the most recent epochs since the planet recovery. The solutions favor a low-eccentricity orbit e ≈ 0.17, with semi-major axis in the range 8-9 AU corresponding to orbital periods of 17-21 yrs. Our solutions favor a highly inclined solution with a peak around i = 88.5 ± 1.7°, and a longitude of ascending node tightly constrained at Ω =-147.5 ± 1.5°. These results indicate that the orbital plane of the planet is likely to be above the midplane of the main disk, and compatible with the warp component of the disk being tilted between 3.5 deg and 4.0 deg. This suggests that the planet plays a key role in the origin of the inner warped-disk morphology of the β Pic disk. Finally, these orbital parameters are consistent with the hypothesis that the planet is responsible for the transit-like event observed in November 1981, and also linked to the cometary activity observed in the β Pic system. © 2012 ESO.
• Lagrange, A. -., Boccaletti, A., Milli, J., Chauvin, G., Bonnefoy, M., Mouillet, D., Augereau, J. C., Girard, J. H., Lacour, S., & Apai, D. (2012). The position of β Pictoris b position relative to the debris disk. Astronomy and Astrophysics, 542.
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  Abstract: Context. We detected in 2009 a giant, close-by planet orbiting β Pic, a young star surrounded by a disk that has been extensively studied for more than 20 years. We showed that if the planet were located on an inclined orbit, this could account for several peculiarities of the β Pictoris system. However, the available data did not permit us to measure the inclination of β Pic b with respect to the disk, and in particular to establish in which component of the disk-either the main, extended disk or the inner inclined component/disk-the planet was located. Comparison between the observed planet position and the disk orientation measured using previous imaging data was not an option because of potential biases in the measurements. Aims. Our aim is to measure precisely the planet location with respect to the dust disk using a single high-resolution image, and correcting for systematics or errors that degrade the precision of the disk and planet relative-position measurements. Methods. We gathered new NaCo data in the Ks band, with a set-up optimized to derive simultaneously the orientation(s) of the disk(s) and the planet projected position. Results. We show that the projected position of β Pic b is above the midplane of the main disk. With the current data and knowledge of the system, this implies that β Pic b cannot be located in the main disk. The data instead suggest that the planet is located in the inclined component. © 2012 ESO.
• Quanz, S. P., Birkmann, S. M., Apai, D., Wolf, S., & Henning, T. (2012). Resolving the inner regions of the HD 97048 circumstellar disk with VLT/NACO polarimetric differential imaging. Astronomy and Astrophysics, 538.
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  Abstract: Context. Circumstellar disks are the cradles of planetary systems and their physical and chemical properties directly influence the planet formation process. Because most planets supposedly form in the inner disk regions, i.e., within a few tens of AU, it is crucial to study circumstellar disks on these scales to constrain the conditions for planet formation. Aims. Our aims are to characterize the inner regions of the circumstellar disk around the young Herbig Ae/Be star HD 97048 in polarized light. Methods. We used VLT/NACO to observe HD 97048 in polarimetric differential imaging (PDI) mode in the H and K s band. This technique offers high-contrast capabilities at very small inner working angles and probes the dust grains on the surface layer of the disk that act as the scattering surface. Results. We spatially resolve the disk around HD 97048 in polarized flux in both filters on scales between -0.1″-1.0″ corresponding to the inner -16-160 AU. Fitting isophots to the flux calibrated H-band image between 13-14 mag/arcsec 2 and 14-15 mag/arcsec 2, we derive an apparent disk inclination angle of 34° ± 5° and 47° ± 2°, respectively. The disk position angle in both brightness regimes is almost identical and roughly 80°. Along the disk major axis the surface brightness of the polarized flux drops from -11 mag/arcsec 2 at -0.1″ (-16 AU) to -15.3 mag/arcsec 2 at - 1.0″ (-160 AU). The brightness profiles along the major axis are fitted with power-laws falling off as r - 1.78 ± 0.02 in H and r - 2.34 ± 0.04 in K s. Because the surface brightness decreases more rapidly in K s compared to H, the disks becomes relatively bluer at larger separations, possibly indicating changing dust grain properties as a function of radius. Conclusions. We imaged for the first time the inner -0.1″-1.0″ (-16-160 AU) of the surface layer of the HD 97048 circumstellar disk in scattered light, which demonstrates the power of ground-based imaging polarimetry. Our data fill an important gap in a large collection of existing data that include resolved thermal dust and polycyclic aromatic hydrocarbon (PAH) emission and also resolved gas emission lines. HD 97048 therefore is an ideal test case for sophisticated models of circumstellar disks and a prime target for future high-contrast imaging observations. © ESO, 2012.
• Rodigas, T. J., Hinz, P. M., Leisenring, J., Vaitheeswaran, V., Skemer, A. J., Skrutskie, M., Su, K. Y., Bailey, V., Schneider, G., Close, L., Mannucci, F., Esposito, S., Arcidiacono, C., Pinna, E., Argomedo, J., Agapito, G., Apai, D., Bono, G., Boutsia, K., , Briguglio, R., et al. (2012). The Gray Needle: Large Grains in the HD 15115 Debris Disk from LBT/PISCES/Ks and LBTI/LMIRcam/L' Adaptive Optics Imaging. apj, 752, 57.
• Bonnefoy, M., Lagrange, A. -., Boccaletti, A., Chauvin, G., Apai, D., Allard, F., Ehrenreich, D., Girard, J. H., Mouillet, D., Rouan, D., Gratadour, D., & Kasper, M. (2011). High angular resolution detection of β Pictoris b at 2.18 μ m. Astronomy and Astrophysics, 528.
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  Abstract: Context. A giant planet was recently discovered around the young star β Pictoris. This planet is the closest to its parent star ever imaged. With an estimated mass of about 9 MJup and separation of 8-15 AU, it explains most of the peculiarities of β Pictoris and its disk. Aims. Previous detections were made in the L′ band (3.8 μm) and at 4.05 μm. We recorded new Ks-band data (2.18 μm) in order to measure its color and get an additional estimate of its mass and effective temperature Methods. Angular differential Ks-band images of β Pictoris were recorded with NaCo in March and April 2010. Results. The companion is detected at Ks. This independently confirms the physical nature of β Pictoris b inferred from the L′ and NB-4.05 bands. The increase of the projected separation between October-December 2009 and April 2010 observations is consistent within error bars with the expected orbital motion. Using the absolute Ks photometry, "hot start" evolutionary models predict a mass of 7-11 MJup in agreement with previous estimates. Moreover, this mass is compatible with Teff = 1700 ± 300 K derived from the comparison of the Ks - L′ color with those generated using synthetic spectra. © 2011 ESO.
• Kun, M., Szegedi-Elek, E., Moór, A., Brahm, P., Acosta-Pulido, J., Apai, D., Kelemen, J., Pl, A., Rcz, M., Regly, Z., Szakts, R., Szalai, N., & Szing, A. (2011). A peculiar young eruptive star in the dark cloud Lynds 1340. Astrophysical Journal Letters, 733(1 PART 2).
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  Abstract: We conducted a long-term optical photometric and spectroscopic monitoring of the strongly variable, accreting young sun-like star [KOS94] HA11, associated with the dark cloud Lynds 1340 that exhibited large amplitude (5-6 mag in the I C band) brightness variations on 2-3 years timescales, flat spectral energy distribution (SED), and extremely strong (300≲ EW/ ≲ 900) Hα emission. In this Letter we describe the basic properties of the star, derived from our observations between 1999 and 2011, and put into context the observed phenomena. The observed variations in the emission spectra, near-infrared colors, and SED suggest that [KOS94] HA11 (spectral type: K7-M0) is an eruptive young star, possibly similar in nature to V1647 Ori: its large-scale photometric variations are governed by variable accretion rate, associated with variations in the inner disk structure. The star recently has undergone strong and rapid brightness variations, thus its further observations may offer a rare opportunity for studying structural and chemical rearrangements of the inner disk, induced by variable central luminosity. © 2011. The American Astronomical Society. All rights reserved.
• Kun, M., Szegedi-Elek, E., Moór, A., Kóspál, Á., Ábrahám, P., Apai, D., Kiss, Z. T., Klagyivik, P., Magakian, T. Y., Mezo, G., Movsessian, T. A., Pál, A., Rácz, M., & Rogers, J. (2011). Inner disc rearrangement revealed by dramatic brightness variations in the young star PVCep. Monthly Notices of the Royal Astronomical Society, 413(4), 2689-2695.
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  Abstract: Young Sun-like stars at the beginning of the pre-main-sequence (PMS) evolution are surrounded by accretion discs and remnant protostellar envelopes. Photometric and spectroscopic variations of these stars are driven by interactions of the star with the disc. Time-scales and wavelength dependence of the variability carry information on the physical mechanisms behind these interactions. We conducted multi-epoch, multiwavelength study of PVCep, a strongly variable, accreting PMS star. By combining our own observations from 2004 to 2010 with archival and literature data, we show that PVCep started a spectacular fading in 2005, reaching an IC-band amplitude of 4mag. Analysis of variation of the optical and infrared fluxes, colour indices and emission line fluxes suggests that the photometric decline in 2005-2009 resulted from an interplay between variable accretion and circumstellar extinction: since the central luminosity of the system is dominated by accretion, a modest drop in the accretion rate could induce the drastic restructuring of the inner disc. Dust condensation in the inner disc region might have resulted in the enhancement of the circumstellar extinction. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.
• Apai, D., Lagerstrom, J., Reid, I. N., Levay, K. L., Fraser, E., Nota, A., & Henneken, E. (2010). Lessons from a high-impact observatory: The Hubble Space Telescope's science productivity between 1998 and 2008. Publications of the Astronomical Society of the Pacific, 122(893), 808-826.
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  Abstract: Almost two decades of continuous operation of the versatile and productive Hubble Space Telescope (HST) provide uniquely well-documented, robust statistics to study the scientific impact of a major astronomical observatory. We compiled a detailed database of refereed articles that use HST data for analysis and show it to be >95% complete. This HST Publication Database is publicly available and searchable: it contains more than 8700 articles, cited more than 300,000 times in the literature. By cross-linking this data set with our extensive proposal database and NASA's ADS service, we are able to trace the evolution of ideas from the proposal stage through the observations and publication steps to the final impact on the astronomical literature. Here we present a detailed study of HST's performance, including the temporal evolution of the publication rate, the citation statistics, the relative contributions from different program types, the time allocation strategy, and the relative contributions of the HST instruments. We also discuss the properties of typical and very highly-cited articles. By analyzing this complete and well-characterized database, we identify five key features that contribute to the productivity and high impact of the observatory: (1) the time allocation policies; (2) the well-characterized HST archive; (3) the breadth of science projects ranging from the solar system to cosmology; (4) the Director's Discretionary time allocations; (5) the large international user community and its involvement in the observatory's functions. In addition, we find the following general characteristics. Following its launch, HST's productivity has been steadily increasing; 8 yr after launch, HST reached equilibrium between the incoming data volume and the number of published articles that are based on those data. The overall productivity, however, is still steadily increasing due to the increasing number of archival articles. We find that small programs produce more citations per orbit than large programs, but only large programs have the potential to lead to very high-impact articles and data sets with lasting legacy value. We find that while typical HST articles receive the largest number of citations 2-3 yr after publication and exhibit a subsequent decline, the most-cited articles show a qualitatively different citation history. Together these results provide a detailed picture of HST's science productivity and identify key characteristics that contribute to making HST a high-impact observatory. © 2010. The Astronomical Society of the Pacific. All rights reserved.
• Lagrange, A. -., Bonnefoy, M., Chauvin, G., Apai, D., Ehrenreich, D., Boccaletti, A., Gratadour, D., Rouan, D., Mouillet, D., Lacour, S., & Kasper, M. (2010). A giant planet imaged in the disk of the young star β pictoris. Science, 329(5987), 57-59.
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  PMID: 20538914;Abstract: Here, we show that the ∼10-million-year-old β Pictoris system hosts a massive giant planet, β Pictoris b, located 8 to 15 astronomical units from the star. This result confirms that gas giant planets form rapidly within disks and validates the use of disk structures as fingerprints of embedded planets. Among the few planets already imaged, β Pictoris b is the closest to its parent star. Its short period could allow for recording of the full orbit within 17 years. Copyright 2010 by the American Association for the Advancement of Science; all rights reserved.
• Lagrange, A., Bonnefoy, M., Chauvin, G., Apai, D., Ehrenreich, D., Boccaletti, A., Gratadour, D., Rouan, D., Mouillet, D., Lacour, S., & Kasper, M. (2010). The planet companion around β Pictoris. Proceedings of the International Astronomical Union, 6(S276), 60-63.
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  Abstract: The β Pic disk of dust and gas has been regarded as the prototype of young planetary systems since the 1980s and has revealed over the years an impressive amount of indirect signs pointing toward the presence of at least one giant planet. We present here the recently detected first giant planet around this star. We show how this planet could explain some very peculiar features of the star environment (disk, spectroscopic variability), and how it constrains the scenarios of planetary system formation (timescales, mechanisms). © International Astronomical Union 2011.
• López-Morales, M., Coughlin, J. L., Sing, D. K., Burrows, A., Apai, D., Rogers, J. C., Spiegel, D. S., & Adams, E. R. (2010). Day-side z′-band emission and eccentricity of wasp-12b. Astrophysical Journal Letters, 716(1 PART 2), L36-L40.
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  Abstract: We report the detection of the eclipse of the very hot Jupiter WASP-12b via z′-band time-series photometry obtained with the 3.5 m Astrophysical Research Consortium telescope at Apache Point Observatory. We measure a decrease in flux of 0.082% 0.015% during the passage of the planet behind the star. That planetary flux is equally well reproduced by atmospheric models with and without extra absorbers, and blackbody models with f ≥ 0.585 ± 0.080. It is therefore necessary to measure the planet at other wavelengths to further constrain its atmospheric properties. The eclipse appears centered at phase φ = 0.5100+0.0072-0.0061, consistent with an orbital eccentricity of |ecos ω| = 0.016+0.011-0.009 (see note at the end of Section 4). If the orbit of the planet is indeed eccentric, the large radius of WASP-12b can be explained by tidal heating. © 2010. The American Astronomical Society. All rights reserved.
• Rogers, J. C., Apai, D., López-Morales, M., Sing, D. K., & Burrows, A. (2010). Erratum: Ks-band detection of thermal emission and color constraints to CoRoT-1b: A low-albedo planet with inefficient atmospheric energy redistribution and a temperature inversion(Astrophysical Journal (2009) 707 (1707)). Astrophysical Journal Letters, 723(2), 1825-1826.
• Apai, D. (2009). Origins of planetary systems: Constraints and challenges. Earth, Moon and Planets, 105(2-4), 311-320.
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  Abstract: The study of planet formation is a field that uniquely benefits from both astronomical observations and laboratory studies of primitive meteoritic material left over from the forming Solar System. We concisely review the key constraints from these studies and place them in the frame of the theoretical models. Four major open problems are identified that can be addressed with next-generation ground-based telescopes: (1) The injection of radionucleids to protoplanetary disks; (2) Protostellar collapse and the formation of the first solids; (3) Thermal processing of protoplanetary materials; (4) Disk-planet interactions and disk dispersal. © Springer Science+Business Media B.V. 2009.
• Grady, C. A., Schneider, G., Sitko, M. L., Williger, G. M., Hamaguchi, K., Brittain, S. D., Ablordeppey, K., Apai, D., Beerman, L., Carpenter, W. J., Collins, K. A., Fukagawa, M., Hammel, H. B., Henning, T., Hines, D., Kimes, R., Lynch, D. K., Ménard, F., Pearson, R., , Russell, R. W., et al. (2009). Revealing the structure of a pre-transitional disk: The case of the herbig F star SAO 206462 (HD 135344B). Astrophysical Journal Letters, 699(2), 1822-1842.
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  Abstract: SAO 206462 (HD 135344B) has previously been identified as a Herbig F star with a circumstellar disk with a dip in its infrared excess near 10 μm. In combination with a low accretion rate estimated from Br γ, it may represent a gapped, but otherwise primordial or "pre-transitional" disk. We test this hypothesis with Hubble Space Telescope coronagraphic imagery, FUV spectroscopy and imagery and archival X-ray data, and spectral energy distribution (SED) modeling constrained by the observed system inclination, disk outer radius, and outer disk radial surface brightness (SB) profile using the Whitney Monte Carlo Radiative Transfer Code. The essentially face-on (i ≲ 20°) disk is detected in scattered light from 04 to 115 (56-160 AU), with a steep (r -9.6) radial SB profile from 06 to 093. Fitting the SB data requires a concave upward or anti-flared outer disk, indicating substantial dust grain growth and settling by 8 4 Myr. The warm dust component is significantly variable in near to mid-IR excess and in temperature. At its warmest, it appears confined to a narrow belt from 0.08 to 0.2 AU. The steep SED for this dust component is consistent with grains with a≤ 2.5 μm. For cosmic carbon to silicate dust composition, conspicuous 10 μm silicate emission would be expected and is not observed. This may indicate an elevated carbon to silicate ratio for the warm dust, which is not required to fit the outer disk. At its coolest, the warm dust can be fit with a disk from 0.14 to 0.31 AU, but with a higher inclination than either the outer disk or the gaseous disk, providing confirmation of the high inclination inferred from mid-IR interferometry. In tandem, the compositional and inclination difference between the warm dust and the outer dust disk suggests that the warm dust may be of second-generation origin, rather than a remnant of a primordial disk component. With its near face-on inclination, SAO 206462's disk is a prime location for planet searches. © 2009. The American Astronomical Society. All rights reserved.
• Grady, C. A., Schneider, G., Sitko, M. L., Williger, G. M., Hamaguchi, K., Brittain, S. D., Ablordeppey, K., Apai, D., Beerman, L., Carpenter, W. J., Collins, K. A., Fukagawa, M., Hammel, H. B., Henning, T., Hines, D., Kimes, R., Lynch, D. K., Pearson, R., Russell, R. W., , Ménard, F., et al. (2009). The disk and environment of a young altair analog: SAO 206462. AIP Conference Proceedings, 1094, 385-388.
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  Abstract: Proto-planetary and transitional disks which are detected in scattered light provide a critical test of the interpretation of circumstellar disks based on the IR spectral energy distribution (SED) alone. The disk inclination to the line-of-sight, outter radius, and surface brightness (SB) maps or radial SB distributions provided by spatially resolved imaging remove most of the degeneracies inherent in fitting IR SEDs without such observational constraints. We have imaged the disk of SAO 206462 (HD 135344B) in 1.1 and 1.6μm scattered light with HST/NICMOS and can trace the essentially face-on disk out to 1.05". The cavity detected in sub-mm observations lies entirely under the NICMOS coronagraphic spot, a result consistent with the SED fitting if the star is at d=140pc. The SED had previously been classified as a Meeus Group I SED and interpreted as arising in a flared disk. Neither the 1.1 nor the 1.6μm radial surface brightness profiles are consistent with a flared disk. A FUSE FUV spectrum demonstrates the presence of excess light in this system, confirming the accretion rate estimated from Brγ. Collectively, these data strengthen the interpretation of this system as a transitional disk. © 2009 American Institute of Physics.
• Janson, M., Apai, D., Zechmeister, M., Brandner, W., Kürster, M., Kasper, M., Reffert, S., Endl, M., Lafrenière, D., Geißler, K., Hippler, S., & Henning, T. (2009). Imaging search for the unseen companion to ε Ind A - Improving the detection limits with 4 μm observations. Monthly Notices of the Royal Astronomical Society, 399(1), 377-384.
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  Abstract: ε Ind A is one of the nearest Sun-like stars, located only 3.6 pc away. It is known to host a binary brown dwarf companion, ε Ind Ba/Bb, at a large projected separation of 6.7 arcmin, but radial velocity measurements imply that an additional, yet unseen, component is present in the system, much closer to ε Ind A. Previously, direct imaging has excluded the presence of any stellar or high-mass brown dwarf companion at small separations, indicating that the unseen companion may be a low-mass brown dwarf or high-mass planet. We present the results of a deep high-contrast imaging search for the companion, using active angular differential imaging at 4 μm, a particularly powerful technique for planet searches around nearby and relatively old stars. We also develop an additional point spread function reference subtraction scheme based on locally optimized combination of images to further enhance the detection limits. No companion is seen in the images, although we are sensitive to significantly lower masses than previously achieved. Combining the imaging data with the known radial velocity trend, we constrain the properties of the companion to within approximately 5-20 Mjup, 10-20 au and i > 20°, unless it is an exotic stellar remnant. The results also imply that the system is probably older than the frequently assumed age of ∼1 Gyr. © 2009 RAS.
• Lagrange, A. -., Kasper, M., Boccaletti, A., Chauvin, G., Gratadour, D., Fusco, T., Ehrenreich, D., Apai, D., Mouillet, D., & Rouan, D. (2009). Constraining the orbit of the possible companion to Β pictoris. Astronomy and Astrophysics, 506(2), 927-934.
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  Abstract: Context.We recently reported on the detection of a possible planetary mass companion to β Pictoris at a projected separation of 8 AU from the star, using data taken in November 2003 with NaCo, the adaptive-optics system installed on the Very Large Telescope UT4. Even though no second epoch detection was available, there are strong arguments to favor a gravitationally bound companion rather than a background object. If confirmed and located at a physical separation of 8 AU, this companion would be the closest planet ever imaged, and above all, could have formed via core-accretion. Its apparent magnitude would indicate a typical temperature of ∼1500 K and a mass of ∼8 MJup. Interestingly, a planet with such characteristics would explain the main morphological and dynamical peculiarities of the β Pic system. Aims.Our goal was to re-observe β Pic five years later to again detect the companion or, in the case of a non-detection, constrain its orbit. Methods. Deep adaptive-optics L'-band direct images of β Pic as well as Ks-band Four Quadrant Phase Mask coronagraph images with were recorded with NaCo. Results. No point-like signal with the brightness of the companion candidate (apparent magnitudes L' = 11.2 or Ks ≃ 12.5) was detected at projected distances down to ≃6.5 AU in the present data from the star (by comparison, the same limit was reached at ≃5.5 AU in the better quality November 2003 data). As expected, the non detection does not allow us to rule out a background companion from an observational point of view. We show that the non detection is consistent with orbital motion. Using these data and previous Ks-band data obtained in 2004, we place strong constraints on the possible orbits of the companion. © 2009 ESO.
• Rogers, J. C., Apai, D., López-Morales, M., Sing, D. K., & Burrows, A. (2009). Ks-band detection of thermal emission and color constraints to corot-1b: A low-albedo planet with inefficient atmospheric energy redistribution and a temperature inversion. Astrophysical Journal Letters, 707(2), 1707-1716.
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  Abstract: We report the detection in Ks-band of the secondary eclipse of the hot Jupiter CoRoT-1b from time series photometry with the ARC 3.5 m telescope at Apache Point Observatory. The eclipse shows a depth of 0.336 0.042% and is centered at phase 0.5022+0.0023-0.0027, consistent with a zero eccentricity orbit (e cos ω = 0.0035+0.0036-0.0042). We perform the first optical to near-infrared multi-band photometric analysis of an exoplanet's atmosphere and constrain the reflected and thermal emissions by combining our result with the recent 0.6, 0.71, and 2.09 μm secondary eclipse detections by Snellen etal., Gillon etal., and Alonso etal. Comparing the multi-wavelength detections to state-of-the-art radiative-convective chemical-equilibrium atmosphere models, we find the near-infrared fluxes difficult to reproduce. The closest blackbody-based and physical models provide the following atmosphere parameters: a temperature T = 2460+80-160 K; a very low Bond albedo AB = 0.000+0.081-0.000; and an energy redistribution parameter Pn = 0.1, indicating a small but nonzero amount of heat transfer from the day to nightside. The best physical model suggests a thermal inversion layer with an extra optical absorber of opacity κe = 0.05cm2g-1, placed near the 0.1 bar atmospheric pressure level. This inversion layer is located 10 times deeper in the atmosphere than the absorbers used in models to fit mid-infrared Spitzer detections of other irradiated hot Jupiters. © 2009 The American Astronomical Society.
• Dullemond, C., Pavlyuchenkov, Y., Apai, D., & Pontoppidan, K. (2008). Structure and evolution of protoplanetary disks. Journal of Physics: Conference Series, 131.
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  Abstract: We present here a few thoughts on how high-angular resolution observations can give clues to some properties of protoplanetary disks that are fundamental to theories of planet formation. High-angular resolution infrared spectroscopy, either with a large single mirror telescope, or by using infrared interferometry, allows us to probe the abundance of thermally processed dust in the disk as a function of distance to the star. We show that this radial abundance profile can give information about the early evolution of the protoplanetary disk as well as about the nature of the turbulence. Since turbulence is one of the main ingredients in theories of planet formation, this latter result is particularly important. We also show that Nature itself provides an interesting way to perform high-angular resolution observations with intermediate-angular resolution telescopes: if a disk has a (nearly) edge-on orientation and is located in a low-density ambient dusty medium, the disk casts a shadow into this medium, as it blocks the starlight in equatorial direction. We argue how these shadows can be used to characterize the dust in the disk. © 2008 IOP Publishing Ltd.
• Kóspál, Á., Ábrahám, P., Apai, D., Ardila, D. R., Grady, C. A., Henning, T., Juhász, A., Miller, D. W., & Moór, A. (2008). High-resolution polarimetry of Parsamian 21: Revealing the structure of an edge-on FU Ori disc. Monthly Notices of the Royal Astronomical Society, 383(3), 1015-1028.
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  Abstract: We present the first high spatial resolution near-infrared direct and polarimetric observations of Parsamian 21, obtained with the Nasmyth Adaptive Optics System-CONICA instrument at the Very Large Telescope (VLT). We complemented these measurements with archival infrared observations, such as Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 (WFPC2) imaging, HST/Near Infrared Camera and Multi-Object Spectrometer (NICMOS) polarimetry, photometry with the Spitzer Space Telescope's Infrared Array Camera (IRAC) and Multiband Imaging Photometer (MIPS), spectroscopy with Spitzer's Infrared Spectrograph (IRS), as well as Infrared Space Observatory (ISO) photometry. Our main conclusions are as follows: (1) we argue that Parsamian 21 is probably an FU Orionis-type object (FUor); (2) Parsamian 21 is not associated with any rich cluster of young stars; (3) our measurements reveal a circumstellar envelope, a polar cavity and an edge-on disc; the disc seems to be geometrically flat and extends from approximately 48 to 360 au from the star; (4) the spectral energy distribution (SED) can be reproduced with a simple model of a circumstellar disc and an envelope; (5) within the framework of an evolutionary sequence of FUors proposed by Green et al. and Quanz et al., Parsamian 21 can be classified as an intermediate-aged object. © 2007 RAS.
• Apai, D., Bik, A., Kaper, L., Henning, T., & Zinnecker, H. (2007). Massive binaries in high-mass star-forming regions: A multiepoch radial velocity survey of embedded O stars. Astrophysical Journal, 655(1 I), 484-491.
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  Abstract: We present the first multiepoch radial velocity study of embedded young massive stars using near-infrared spectra obtained with ISAAC mounted at the ESO Very Large Telescope, with the aim of detecting massive binaries. Our 16 targets are located in high-mass star-forming regions, and many of them are associated with known ultracompact H II regions, whose young age ensures that dynamic evolution of the clusters did not influence the intrinsic binarity rate. We identify two stars with about 90 km s-1 velocity differences between two epochs, proving the presence of close massive binaries. The fact that two out of the 16 observed stars are binary systems suggests that at least 20% of the young massive stars are formed in close multiple systems, but may also be consistent with most, if not all, young massive stars being binaries. In addition, we show that the radial velocity dispersion of the full sample is about 35 km s-1, significantly larger than our estimated uncertainty (25 km s-1). This finding is consistent with similar measurements of the young massive cluster 30 Dor, which might have a high intrinsic binary rate. Furthermore, we argue that virial cluster masses derived from the radial velocity dispersion of young massive stars may intrinsically overestimate the cluster mass due to the presence of binaries. © 2007. The American Astronomical Society. All rights reserved.
• Kasper, M., Apai, D., Janson, M., & Brandner, W. (2007). A novel L-band imaging search for giant planets in the Tucana and β Pictoris moving groups. Astronomy and Astrophysics, 472(1), 321-327.
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  Abstract: Context. Direct imaging using various techniques for suppressing the stellar halo nowadays can achieve the contrast levels required to detect and characterize the light of substellar companions at orbital distances greater than a few astronomical units from their host stars. The method nicely complements the radial velocity surveys that provide evidence that giant extrasolar planets in close-in orbits are relatively common. Aims. The paper presents results from a small survey of 22 young, nearby stars that was designed to detect substellar companions and ultimately giant extrasolar planets down to Jupiter masses. The targets are members of the Tucana and β Pictoris moving groups, apart from the somewhat older star HIP 71395, which has a radial velocity trend suggesting a massive planet in large orbit. Methods. The survey was carried out in the L-band using adaptive optics-assisted imaging with NAOS-CONICA (NACO) at the VLT. The chosen observation wavelength is well-suited to searching for close companions around young stars and it delivers unprecedented detection limits. The presented technique reaches some of the best sensitivities as of today and is currently the most sensitive method for the contrast-limited detection of substellar companions that are cooler than about 1000 K. Results. The companion to 51 Eri, GJ 3305, was found to be a very close binary on an eccentric orbit. No substellar companions were found around the target stars, although the method permitted companions to be detected down to a few Jupiter masses at orbital distances typically of 5 astronomical units. A planet with a mass ≥1 MJup at distances ≥5 AU around AU Mic can be excluded at the time of our observations. The absence of detected planets sets constraints on the frequency distribution and maximum orbital distance of giant exoplanets. For example, a radial distribution power law index of 0.2 in combination with a maximum orbital radius exceeding 30 AU can be rejected at a 90% confidence level. Conclusions. © ESO 2007.
• Quanz, S. P., Apai, D., & Henning, T. (2007). Dust rings and filaments around the isolated young star V1331 Cygni. Astrophysical Journal, 656(1 I), 287-292.
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  Abstract: We characterize the small- and large-scale environment of the young star V1331 Cygni with high-resolution HST WFPC2 and Digitized Sky Survey images. In addition to a previously known outer dust ring (≈30″ in diameter), the WFPC2 scattered light image reveals an inner dust ring for the first time. This ring has a maximum radius of ≈6.5″ and is possibly related to a molecular envelope. Large-scale optical images show that V1331 Cyg is located at the tip of a long dust filament linking it to the dark cloud LDN 981. We discuss the origin of the observed dust morphology and analyze the object's relation to its parent dark cloud LDN 981. Finally, based on recent results from the literature, we investigate the properties of V1331 Cyg and conclude that in its current state the object does not show sufficient evidence to be characterized as an FU Ori object. © 2007. The American Astronomical Society. All rights reserved.
• Dullemond, C. P., Apai, D., & Walch, S. (2006). Crystalline silicates as a probe of disk formation history. Astrophysical Journal Letters, 640(1 II), L67-L70.
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  Abstract: We present a new perspective on the crystallinity of dust in protoplanetary disks. The dominant crystallization by thermal annealing happens in the very early phases of disk formation and evolution. Both the disk properties and the level of crystallinity are thereby directly linked to the properties of the molecular cloud core from which the star+disk system was formed. We show that under the assumption of single-star formation, rapidly rotating clouds produce disks that after the main infall phase (i.e., in the optically revealed class II phase) are rather massive and have a high accretion rate but low crystallinity. Slowly rotating clouds, on the other hand, produce less massive disks with lower accretion rates but high levels of crystallinity. Cloud fragmentation and the formation of multiple stars complicates the problem and necessitates further study. The underlying physics of the model is insufficiently understood to provide the precise relationship between crystallinity, disk mass, and accretion rate. But the fact that with "standard" input physics the model produces disks that, in comparison to observations, appear to have either too high levels of crystallinity or too high disk masses demonstrates that the comparison of these models to observations can place strong constraints on the disk physics. The question to ask is not why some sources are so crystalline, but why some other sources have such a low level of crystallinity. © 2006. The American Astronomical Society. All rights reserved.
• Moór, A., Ábrahám, P., Derekas, A., Kiss, C., Kiss, L. L., Apai, D., Grady, C., & Henning, T. (2006). Nearby debris disk systems with high fractional luminosity reconsidered. Astrophysical Journal Letters, 644(1), 525-542.
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  Abstract: By searching the IRAS and ISO databases, we compiled a list of 60 debris disks that exhibit the highest fractional luminosity values (fd > 10-4) in the vicinity of the Sun (d < 120 pc). Eleven out of these 60 systems are new discoveries. Special care was taken to exclude bogus disks from the sample. We computed the fractional luminosity values using available IRAS, ISO, and Spitzer data and analyzed the Galactic space velocities of the objects. The results revealed that stars with disks of high fractional luminosity often belong to young stellar kinematic groups, providing an opportunity to obtain improved age estimates for these systems. We found that practically all disks with fd > 5 × 10-4 are younger than 100 Myr. The distribution of the disks in the fractional luminosity versus age diagram indicates that (1) the number of old systems with high fd is lower than was claimed before, (2) there exist many relatively young disks of moderate fractional luminosity, and (3) comparing the observations with a current theoretical model of debris disk evolution, a general good agreement could be found. © 2006, The American Astronomical Society. All rights reserved.
• Puga, E., Feldt, M., Alvarez, C., Henning, T., Apai, D., Coarer, E. L., Chalabaev, A., & Stecklum, B. (2006). Outflows, disks, and stellar content in a region of high-mass star formation: G5.89-0.39 with adaptive optics. Astrophysical Journal Letters, 641(1 I), 373-382.
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  Abstract: We present adaptive optics (AO)-assisted near-infrared Fabry-Perot observations of both the H2 v = 1-0 5(1) line in the area surrounding the shell-like ultracompact H II region (UCH II) G5.89-0.39 and the Bry emission in the region of ionized gas. This work aims at investigating the near-IR counterpart to the widely debated massive outflow detected toward this source. We also study the connection of the outflow(s) with the possible driving source(s) to better constrain the stellar content within this UCH II region. Our data show evidence of a total of three outflows in this region, with distinct orientations and different driving sources. Two prominent bow-shock structures are identified in our H2 data in a north-south orientation. The molecular jet, likely associated with these features, is not compatible with the orientation of the outflow previously detected at high spatial resolution in SiO emission. Moreover, we propose the driving source of this jetlike structure as the O5 V star recently detected by Feldt and coworkers. However, we report the detection of a bipolar structure, separated by a dark lane, at the location of the 1.3 mm continuum source (i.e., the candidate source to power the SiO outflow). Finally, a third bipolar outflow is traced through the Brγ emission. The confirmation through CO interferometric observations of this outflow activity would therefore favor an accretion scenario for high-mass star formation. © 2006. The American Astronomical Society. All rights reserved.
• Apai, D., Linz, H., Henning, T., & Stecklum, B. (2005). Infrared portrait of the nearby massive star-forming region IRAS 09002-4732. Astronomy and Astrophysics, 434(3), 987-1003.
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  Abstract: We present high-resolution near-infrared and mid-infrared imaging, mid-infrared spectroscopy and millimetre-wavelength continuum observations of the nearby massive star-forming complex IRAS 09002-4732. A rich cluster of young stars displaying near-infrared excess emission is detected. We identify the ionising source of the ultracompact H II region G268.42-0.85 and show that this star is the dominant heating and illuminating source of the region. Spectral type estimates based on different methods are consistent with a star of spectral type O9. The combination of the new observations with literature data allows us to set up the first structural model for the region. We argue that the ultracompact H II region is embedded in the rear side of the southern CS clump. Additionally, we detect several interesting objects. Among these objects are a network of dark dust filaments, an elongated, externally heated object with strong infrared excess inside the H II region and objects seen as silhouettes in the foreground of the large southern reflection nebulosity. The filamentary structures may play an important role in the star formation process. © ESO 2005.
• Apai, D., Tóth, L., Henning, T., Vavrek, R., Kovács, Z., & Lemke, D. (2005). HST/NICMOS observations of a proto-brown dwarf candidate. Astronomy and Astrophysics, 433(2), L33-L36.
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  Abstract: We present deep HST/NICMOS observations peering through the outflow cavity of the protostellar candidate IRAS 04381+2540 in the Taurus Molecular Cloud-1. A young stellar object as central source, a jet and a very faint and close (0.6″) companion are identified. The primary and the companion have similar colours, consistent with strong reddening. We argue that the companion is neither a shock-excited knot nor a background star. The colour/magnitude information predicts a substellar upper mass limit for the companion, but the final confirmation will require spectroscopic information. Because of its geometry, young age and its rare low-mass companion, this system is likely to provide a unique insight into the formation of brown dwarfs. © ESO 2005.
• Grady, C. A., Woodgate, B., Torres, C. A., Henning, T., Apai, D., Rodmann, J., Wang, H., Stecklum, B., Linz, H., Williger, G. M., Brown, A., Wilkinson, E., Harper, G. M., Herczeg, G. J., Danks, A., Vieira, G. L., Malumuth, E., Collins, N. R., & Hill, R. S. (2004). The environment of the optically brightest Herbig Ae star, HD 104237. Astrophysical Journal Letters, 608(2 I), 809-830.
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  Abstract: We investigate the environment of the nearest Herbig Ae star, HD 104237, with a multiwavelength combination of optical coronagraphic, near-IR, and mid-IR imaging supported by optical, UV, and far-ultraviolet spectroscopy. We confirm the presence of T Tauri stars associated with the Herbig Ae star HD 104237, noted by Feigelson et al. We find that two of the stars within 15″ of HD 104237 have IR excesses, potentially indicating the presence of circumstellar disks, in addition to the Herbig Ae star itself. We derive a new spectral type of A7.5Ve-A8Ve for HD 104237 and find log (L/L⊙) = 1.39. With these data, HD 104237 has an age of t ≈ 5 Myr, in agreement with the estimates for the other members of the association. HD 104237 is still actively accreting, with a conspicuous UV/far-UV excess seen down to 1040 Å, and is driving a bipolar microjet termed HH 669. This makes it the second, older Herbig Ae star now known to have a microjet. The presence of the microjet enables us to constrain the circumstellar disk to r ≤ 0″.6 (70 AU) with an inclination angle of z = 18°-11+14 from pole-on. The absence of a spatially extended continuum and fluorescent H2 emission near Lyα is in agreement with the prediction of shadowed disk models for the IR spectral energy distribution. With the high spatial density of disks in this group of stars, proximity, and minimal reddening, HD 104237 and its companions should serve as ideal laboratories for probing the comparative evolution of planetary systems.
• Wang, H., Mundt, R., Henning, T., & Apai, D. (2004). Optical outflows in the R Coronae Australis molecular cloud. Astrophysical Journal Letters, 617(2 I), 1191-1203.
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  Abstract: A deep [S II] λλ6717/6731 wide-field survey of Herbig-Haro (HH) objects has been carried out in two fields toward the R CrA molecular cloud using the ESO/MPG 2.2m Wide Field Imager. Twelve new HH objects, many of which consist of several condensations or knots, have been discovered, and new details of the known HH objects have been revealed. Combining the results of previous optical, infrared, and millimeter-wavelength observations, the possible exciting sources of HH objects in the region are discussed. On the basis of the previously known and newly discovered HH objects, at least five HH flows in the region around R CrA and at least two outflows in the region around VV CrA can be identified. In combination with the previously detected molecular outflows, the HH flows in the R CrA region indicate rather active star formation in the R CrA core in the past 105-106 yr.
• Stecklum, B., Henning, T., Apai, D., & Linz, H. (2002). VLT-ISAAC observations of massive star-forming regions. Proceedings of SPIE - The International Society for Optical Engineering, 4834, 337-344.
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  Abstract: The high optical quality of ESO's ISAAC instrument at the 8.2-m ANTU VLT telescope and the good observing conditions at the Paranal site allow very detailed studies of southern massive star-forming regions. Our observations revealed their large degree of complexity. By means of near- and thermal-infrared images we performed a thorough characterisation of the embedded stellar population. Imaging polarimetry provided clues on the spatial distribution of the dust grains and the illuminating sources. Special emphasis was put on the most massive objects, young luminous stars that cause ultracompact HII regions.

Proceedings Publications

• Apai, D., Milster, T., Kim, D., Bixel, A., Schneider, G., Rackham, B., & Arenberg, J. (2021, mar). A Search for Life in a Thousand Earths: The Nautilus Space Observatory. In Bulletin of the American Astronomical Society, 53.
• Bixel, A., & Apai, D. (2021, mar). Bioverse: a simulation framework to assess the statistical power of future biosignature surveys. In Bulletin of the American Astronomical Society, 53.
• Dietrich, J., & Apai, D. (2021, mar). Finding Missing Earths: An Integrated Analysis of Multi-planet Systems and Assessing Likelihood of Potentially Habitable Worlds. In Bulletin of the American Astronomical Society, 53.
• Kim, J. S., Fang, M., Clarke, C., Facchini, S., Pascucci, I., Apai, D., & Haworth, T. (2021, mar). External Photoevaporation of Disks around Low Mass Young Stellar and Sub-Stellar Objects. In The 20.5th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (CS20.5).
• Tannock, M. E., Metchev, S., Heinze, A., Miles-P{\'aez}, P., Gagn{\'e}, J., Burgasser, A., Marley, M. S., Apai, D., Suarez, G., & Plavchan, P. (2021, mar). Weather on Other Worlds. V. The Three Most Rapidly Rotating Ultra-Cool Dwarfs. In The 20.5th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (CS20.5).
• Wagner, K., Ertel, S., Stone, J., Leisenring, J., Apai, D., Kasper, M., Absil, O., Close, L., Defr{\`ere}, D., Guyon, O., & Males, J. (2021, sep). Imaging low-mass planets within the habitable zones of nearby stars with ground-based mid-infrared imaging. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11823.
• Apai, D. (2020, jan). "Characterization and Properties of Earth-like Planets". In Origins: From the Protosun to the First Steps of Life, 345.
• Apai, D., Lopez-Morales, M. .., Rackham, B., Espinoza, N., Jordan, A., Osip, D., Bixel, A., McGruder, C., Kirk, J., Weaver, I., Fortney, J., Rodler, F., Lewis, N., & Alam, M. (2020, jan). "The ACCESS Exoplanet Transmission Spectroscopy Survey". In American Astronomical Society Meeting Abstracts #235, 235.
• Apai, D., Milster, T. D., Kim, D., Schneider, G. H., Bixel, A., Benhamin, R., & Jonathan, A. (2020, November). Very Large-diameter, Ultralight Space Telescopes to Enable Large-scale Survey of Candidate Earth-like Planets for Signatures of Life. In ASCEND 2020, 2020, pp 8.
• Apai, D., Milster, T., Kim, D., Bixel, A., Schneider, G., Rackham, B., Liang, R., & Arenberg, J. (2020, jan). Nautilus: A Biosignature Survey in a Thousand Exo-Earths. In American Astronomical Society Meeting Abstracts.
• Arenberg, J., Kim, D., Kim, G. H., Walker, C. K., Choi, H., Apai, D., Spires, O., Milster, T. D., Takashima, Y., Berkson, J., Schneider, G., Esparaza, M., Kim, Y., Quach, H., Fellows, C., Purvin, K., Wang, Z., Zhang, Y., Gaspar, A., , Phan, A., et al. (2020, August 2020). Disruptive space telescope concepts, designs, and developments: OASIS and Nautilus. In Topical Meeting 6 – Frontiers in Optical Metrology (EOS Annual Meeting 2020), 238 (2020), 06001.
• Bixel, A., & Apai, D. (2020, feb). "Identifying Exo-Earth Candidates in Direct Imaging Data Through Bayesian Classification". In Exoplanets in Our Backyard: Solar System and Exoplanet Synergies on Planetary Formation, Evolution, and Habitability, 2195.
• Bixel, A., & Apai, D. (2020, jan). "Identifying Exo-Earth Candidates in Direct Imaging Data Through Bayesian Classification". In American Astronomical Society Meeting Abstracts #235, 235.
• Bixel, A., & Apai, D. (2020, jun). "Testing Earth-like Atmospheric Evolution on Exo-Earths". In American Astronomical Society Meeting Abstracts #236, 236.
• Close}, L. M., Males, J., Long, J. D., Van, G. K., Hedglen, A. D., Kautz, M., Lumbres, J., Haffert, S. Y., Follette, K., Wagner, K., Miller, K., Apai, D., Wu, Y., Guyon, O., Schatz, L., Rodack, A., Doelman, D., Snik, F., Knight, J. M., , Morzinski, K., et al. (2020, dec). "Prediction of the planet yield of the MaxProtoPlanetS high-contrast survey for H-alpha protoplanets with MagAO-X based on first light contrasts". In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 11448.
• Krijt, S., Bosman, A., Zhang, K., Apai, D., & Ciesla, F. (2020, jan). "The CO content of planetary building blocks: Modeling the physical and chemical evolution of protoplanetary disks". In American Astronomical Society Meeting Abstracts #235, 235.
• Krijt, S., Bosman, A., Zhang, K., Apai, D., & Ciesla, F. (2020, jan). The CO content of planetary building blocks: Modeling the physical and chemical evolution of protoplanetary disks. In American Astronomical Society Meeting Abstracts.
• Lew, B., Apai, D., Zhou, Y., Radigan, J., Marley, M., Schneider, G., Cowan, N., Miles-P{'aez}, P., Manjavacas, E., Karalidi, T., Bedin, L., Lowrance, P., & Burgasser, A. (2020, jun). "Cloud Atlas: The rotational modulation of a rare planetary-mass object at the end of L/T transition". In American Astronomical Society Meeting Abstracts #236, 236.
• Mulders, G., Ciesla, F., O'Brien, D., Apai, D., & Pascucci, I. (2020, jan). "The role of planetesimals and gas in the orbital assembly of close-in exoplanets". In American Astronomical Society Meeting Abstracts #235, 235.
• Mulders, G., Ciesla, F., O'Brien, D., Apai, D., & Pascucci, I. (2020, jan). The role of planetesimals and gas in the orbital assembly of close-in exoplanets. In American Astronomical Society Meeting Abstracts.
• Mulders, G., O'Brien, D., Ciesla, F., Apai, D., & Pascucci, I. (2020, oct). "The role of planetesimals and gas in the orbital assembly of close-in exoplanets". In AAS/Division for Planetary Sciences Meeting Abstracts, 52.
• Apai, D., Bixel, A., Rackham, B. V., Schneider, G., Milster, T. D., Kim, D. W., Liang, R., Arenberg, J., & Grunsfeld, J. (2019, sep). Nautilus: A Very Large-Aperture, Ultralight Space Telescope for Exoplanet Exploration, Time-domain Astrophysics, and Faint Objects. In Astro2020 White Paper for Probe-class mission, 51.
• Apai, D., Milster, T. D., Kim, D. W., Bixel, A., Schneider, G., Rackham, B. V., Liang, R., & Arenberg, J. (2019, sep). Nautilus Observatory: a space telescope array based on very large aperture ultralight diffractive optical elements. In procspie, 11116.
• Lew, B. W., Marley, M. S., Apai, D., Zhou, Y., Cowan, N. B., Schneider, G., Karalidi, T., Manjavacas, E., & Bedin, L. R. (2019, sep). Cloud Atlas: Unraveling the Vertical Cloud Structure in Ultracool Atmospheres with Self-consistent Heterogeneous Cloud Models. In EPSC-DPS Joint Meeting 2019, 2019.
• Liang, R., Arenberg, J., Rackham, B. V., Schneider, G., Bixel, A., Kim, D., Milster, T. D., & Apai, D. (2019, September). Nautilus Observatory: a space telescope array based on very large aperture ultralight diffractive optical elements. In Astronomical Optics: Design, Manufacture, and Test of Space and Ground Systems II, 11116, 08.
• McGruder, C., Lopez-Morales, M., Apai, D., Jord{'an}, A., Osip, D., Bixel, A., Espinoza, N., Fortney, J., Kirk, J., Lewis, N., Rackham, B., Rodler, F., & Weaver, I. (2019, aug). ACCESS: the Arizona-CfA-Catolica-Carnegie Exoplanet Spectroscopy Survey. In AAS/Division for Extreme Solar Systems Abstracts, 51.
• Metchev, S., Miles-P{'aez}, P., Palle, E., Zapatero, O., Tannock, M., Apai, D., Artigau, '., Burgasser, A., Mace, G., & Triaud, A. (2019, aug). A Spitzer search for transiting exoplanets around ultra-cool dwarf stars viewed equator-on. In AAS/Division for Extreme Solar Systems Abstracts, 51.
• Mulders, G. D., Mordasini, C., Pascucci, I., Ciesla, F., Emsenhuber, A., & Apai, D. (2019, aug). Exoplanet Population Synthesis in the Era of Large Exoplanets Surveys. In AAS/Division for Extreme Solar Systems Abstracts, 51.
• Rackham, B. V., Apai, D., Giampapa, M. S., Zhang, Z., & Zhou, Y. (2019, jan). The Transit Light Source Effect in F to M Dwarf Systems. In American Astronomical Society Meeting Abstracts #233, 233.
• Rackham, B., Apai, D., Giampapa, M., Espinoza, N., Madhusudhan, N., & Zhou, Y. (2019, sep). Towards Mitigating the Impact of Stellar Photospheric Heterogeneity on Precise Exoplanet Transmission Spectra. In EPSC-DPS Joint Meeting 2019, 2019.
• Wright, J., Allen, V., Alvarado-G{'omez}, J. D., Angerhausen, D., Apai, D., Atri, D., Balbi, A., Barclay, T., Barentsen, G., Beasley, T., Beatty, T., Behmard, A., Berea, A., Boyajian, T., Bridge, J. S., Bryson, S., Bytof, J., Cleaves, H., Colon, K., , Cordes, J., et al. (2019, sep). Searches for Technosignatures: The State of the Profession. In baas, 51.
• Apai, D., Rackham, B., Lopez-Morales, M. .., Espinoza, N., Jordan, A., Osip, D., Lewis, N., Rodler, F., Fraine, J., Morley, C., Fortney, J., Bixel, A., Team, A., & Team, E. (2017, jan). "The ACCESS Transiting Exoplanets Spectroscopy Survey and the Impact of Heterogeneous Stellar Atmospheres on Transit Spectroscopy". In American Astronomical Society Meeting Abstracts, 229.
• Apai}, D., & Team, {. S. (2017, jan). "Extrasolar Storms: Mapping Cloud Cover Evolution with Joint HST-Spitzer Observations". In American Astronomical Society Meeting Abstracts, 229.
• Rackham, B., Apai, D., & Giampapa, M. (2017, oct). "The Effect of Stellar Contamination on Transmission Spectra of Low-mass Exoplanets". In AAS/Division for Planetary Sciences Meeting Abstracts #49, 49.
• Radigan, J., Davis, J., York, B., Apai, D., Marley, M., & Saumon, D. (2017, jan). "Spectral Variability at the L/T Transition and Beyond". In American Astronomical Society Meeting Abstracts, 229.
• Mulders, G., Pascucci, I., & Apai, D. (2016, oct). "The Dependence of the Kepler Planet Population on Host Star Properties". In AAS/Division for Planetary Sciences Meeting Abstracts, 48.
• Rackham, B., Espinoza, N., Apai, D., Lopez-Morales, M. .., Jord{'an}, A., Osip, D., Lewis, N., Rodler, F., Fraine, J., Morley, C., & Fortney, J. (2016, oct). "An Optical Transmission Spectrum of GJ 1214b Suggesting a Heterogeneous Stellar Photosphere". In AAS/Division for Planetary Sciences Meeting Abstracts, 48.
• {Metchev}, S., {Heinze}, A., {Apai}, D., {Flateau}, D., {Radigan}, J., {Burgasser}, A., {Marley}, M., {Artigau}, {., {Plavchan}, P., , B. (2016, jan). Low-gravity L Dwarfs Are Likely More Variable. In IAU Symposium, 314.
• {Mulders}, G., {Pascucci}, I., & Apai, D. (2016, jan). The Dependence of the Kepler Planet Population on Host Star Properties. In American Astronomical Society Meeting Abstracts, 227.
• Buenzli, E., Marley, M., Apai, D., Biller, B., Crossfield, I., & Radigan, J. (2015, dec). Weather in an extremely nearby substellar system. In AAS/Division for Extreme Solar Systems Abstracts, 3.
• Burgasser, A., Radigan, J., Rajan, A., Metchev, S., Showman, A., Zhang, X., Biller, B., Buenzli, E., Marley, M., {Hiranaka}, K., {Best}, W., Morley, C., Sing, D., Apai, D., & Gillon, M. (2015, jan). Splinter Session on Cool Cloudy Atmospheres: Theory and Observations. In 18th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, 18.
• Hanson, J. R., & Apai, D. (2015, jan). KLIP-ing for Analogs - Detection Statistics for HR8799-like systems. In American Astronomical Society Meeting Abstracts, 225, #258.13.
• Radigan, J., Cowan, N. B., Showman, A. P., Apai, D., Metchev, S. A., Marley, M. S., Artigau, E., Burgasser, A. J., Jayawardhana, R., & Goldman, B. (2015, jan). Watching the Weather in Real Time: Spitzer Light Curves of Variable L/T Transition Brown Dwarfs. In American Astronomical Society Meeting Abstracts, 225, #130.06.
• Wells, R., Lopez-Morales, M., Lewis, N., Apai, D., Jordan, A., Espinoza, N., Rackham, B., Osip, D. J., Fraine, J. D., Fortney, J. J., & Rodler, F. (2015, jan). Constraining the Atmospheric Composition of WASP-18b. In American Astronomical Society Meeting Abstracts, 225, #257.01.
• {Espinoza}, N., {Jordan}, A., {Apai}, D., {Lopez-Morales}, M., {Rackham}, B., {Lewis}, N., {Fraine}, J., {Diaz-P{'e}rez}, R., {Rodler}, F., {Wells}, R., , D. (2015, dec). Exploring the diversity of exoplanet atmospheres from the ground with the ACCESS Survey. In AAS/Division for Extreme Solar Systems Abstracts, 3.
• Apai, D. (2014, mar). Search for Life Beyond the Solar System. Exoplanets, Biosignatures & Instruments. In Search for Life Beyond the Solar System. Exoplanets, Biosignatures & Instruments..
• Apai, D. (2014, mar). Search for Life Beyond the Solar System. Exoplanets, Biosignatures amp Instruments. In Search for Life Beyond the Solar System. Exoplanets, Biosignatures amp Instruments.
• Apai, D. (2014, nov). Clouds and Atmospheric Dynamics in Ultracool Atmospheres: HST, Spitzer, and LBT Rotational Mapping of Exoplanets and Brown Dwarfs. In AAS/Division for Planetary Sciences Meeting Abstracts, 46, #204.01.
• Apai, D., Buenzli, E., Flateau, D. C., Metchev, S., Radigan, J., Marley, M. S., Showman, A. P., Reid, I. N., Yang, H., Heinze, A., Karalidi, T., Burgasser, A. J., Lowrance, P., Artigau, E., Mohanty, S., & Storms, S. E. (2014, jan). Spectral Mapping and Long-Term Monitoring: Details and Dynamics of Condensate Cloud Layers. In American Astronomical Society Meeting Abstracts, 223, #425.05.
  More info

  Rotational phase mapping provides exciting new insights into the physical and chemical properties of condensate clouds in brown dwarfs and - soon - in directly imaged exoplanets. In this talk I will show new results from ongoing Hubble Space Telescope spectral mapping projects, which obtain very high quality spectrally and temporally resolved data of rotating brown dwarfs. In addition, simultaneous HST and Spitzer observations allow us to probe cloud layers at multiple atmospheric depths. In the second part of the talk I will discuss how multi-epoch observations of complete rotations can be used to study the evolution of cloud layers and show first results from the Spitzer Cycle-9 Exploration Science program Extrasolar Storms.
• Apai, D., Schneider, G., Grady, C., Wyatt, M., Lagrange, A., Kuchner, M., Stark, C., & Lubow, S. (2014, sep). The Disk Structure and the Planet in the Beta Pictoris System: An HST/STIS Study. In Thirty years of Beta Pic and Debris Disks Studies, 15.
• Close, L. M., Follette, K., Males, J. R., Morzinski, K., Rodigas, T. J., Hinz, P., Wu, Y., Apai, D., Najita, J., Puglisi, A., Esposito, S., Riccardi, A., Bailey, V., Xompero, M., Briguglio, R., & Weinberger, A. (2014, jan). Visible AO Observations at Halpha for Accreting Young Planets. In IAU Symposium, 299, 32-33.
• Espinoza, N., Jord'an, A., Rackham, B., Apai, D., L'opez-Morales, M., Fraine, J., Fortney, J., Lewis, N., & Rodler, F. (2014, mar). A ground-based optical transmission spectrum of WASP-31b. In Search for Life Beyond the Solar System. Exoplanets, Biosignatures amp Instruments, 3P.
• Hinz, P., Esposito, S., Apai, D., Brusa, G., Close, L., Guyon, O., Hill, J., Males, J., Pinna, E., & Puglisi, A. (2014, jul). Toward visible wavelength coherent imaging with the LBT. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 9146, 5.
• Karalidi, T., & Apai, D. (2014, mar). Mapping the atmospheres of other worlds. In Search for Life Beyond the Solar System. Exoplanets, Biosignatures amp Instruments, 2P.
• Lopez-Morales, M., Apai, D., Jordan, A., Espinoza, N., Rackham, B., Fraine, J. D., Rodler, F., Lewis, N., Fortney, J. J., & Osip, D. J. (2014, jun). ACCESS: The Arizona-CfA-Catolica Exoplanet Spectroscopy Survey. In American Astronomical Society Meeting Abstracts, 224, #120.14.
  More info

  The Arizona-CfA-Catolica Exoplanet Spectroscopy Survey (ACCESS) is an international, multi-institutional consortium with members from the Harvard-Smithsonian CfA, the University of Arizona, Pontificia Universidad Catolica in Chile, MIT and UC Santa Cruz and the Carnegie Institution. ACCESS' goal is to observe about two dozen planets covering a wide range of mass, radius, atmospheric temperatures and energy irradiation levels, with two main scientific goals: 1) to obtain, for the first time, a uniform sample of visible transmission spectra of exoplanets, allowing the study of their atmospheric characteristics as a statistically significant sample, and 2) to mature the technique of ground-based observations of exoplanetary atmospheres for future observations of small planets. Here we describe ACCESS and its first science results.
• Mulders, G. D., Ciesla, F., Pascucci, I., & Apai, D. (2014, mar). The Water Content of Exo-earths in the Habitable Zone. In Search for Life Beyond the Solar System. Exoplanets, Biosignatures amp Instruments, 2.
• Mulders, G. D., Pascucci, I., & Apai, D. (2014, nov). Small, numerous and close-in: How occurrence rates of planets around lower-mass stars can constrain planet formation mechanisms.. In AAS/Division for Planetary Sciences Meeting Abstracts, 46, #301.09.
• Rackham, B., Espinoza, N., Apai, D., Jord'an, A., L'opez-Morales, M., Fraine, J., Lewis, N., Rodler, F., Fortney, J., & Osip, D. (2014, mar). Exploring the hot Neptune / super-Earth transition via ground-based transmission spectroscopy. In Search for Life Beyond the Solar System. Exoplanets, Biosignatures amp Instruments, 3P.
• Rackham, B., Espinoza, N., Apai, D., Jordan, A., Lopez-Morales, M., Fraine, J., Lewis, N., Rodler, F., Fortney, J., & Osip, D. (2014, nov). An optical transmission spectrum (4000-10000 AA) of the super-Earth GJ 1214b. In AAS/Division for Planetary Sciences Meeting Abstracts, 46, #104.07.
• Skemer, A. J., Hinz, P., Esposito, S., Skrutskie, M. F., Defr`ere, D., Bailey, V., Leisenring, J., Apai, D., Biller, B., Bonnefoy, M., Brandner, W., Buenzli, E., Close, L., Crepp, J., De Rosa, R. J., Desidera, S., Eisner, J., Fortney, J., Henning, T., , Hofmann, K., et al. (2014, jul). High contrast imaging at the LBT: the LEECH exoplanet imaging survey. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series, 9148, 0.
• Skemer, A., Apai, D., Bailey, V., Biller, B., Bonnefoy, M., Brandner, W., Buenzli, E., Close, L., Crepp, J., Defrere, D., Desidera, S., Eisner, J., Esposito, S., Fortney, J., Henning, T., Hinz, P., Hofmann, K., Leisenring, J., Males, J., , Millan-Gabet, R., et al. (2014, jan). LEECH: A 100 Night Exoplanet Imaging Survey at the LBT. In IAU Symposium, 299, 70-71.
• Yang, H., & Apai, D. (2014, mar). Mapping Cloud Evolution in Brown Dwarf Photospheres. In Search for Life Beyond the Solar System. Exoplanets, Biosignatures amp Instruments, 4P.
• Apai, D., Buenzli, E., Radigan, J., Burrows, A. S., Metchev, S. A., Flateau, D. C., Reid, I. N., Heinze, A., & Jayawardhana, R. (2013, jan). HST and Spitzer Rotational Phase Mapping of Brown Dwarf Atmospheres. In American Astronomical Society Meeting Abstracts, 221, #158.28.
• Buenzli, E., Apai, D., Radigan, J., Morley, C., Burrows, A., Flateau, D., Showman, A., Marley, M., Reid, I. N., Lewis, N., & Jayawardhana, R. (2013, jul). Probing the Heterogeneous Cloud Structure of Variable Brown Dwarfs with HST. In Protostars and Planets VI Posters, 23.
• Mo 'or, A., 'al, '., 'Abrah 'am, P., Juh 'asz, A., Apai, D., Csengeri, T., Grady, C., Henning, T., Kiss, C., & Pascucci, I. (2013, jul). Molecular Gas in Young Debris Disks. In Protostars and Planets VI Posters, 67.
• Zimmerman, N., Skemer, A., Apai, D., Bailey, V., Biller, B., Bonnefoy, M., Brandner, W., Buenzli, E., Close, L., Crepp, J., Defrere, D., Desidera, S., Eisner, J., Esposito, S., Fortney, J., Henning, T., Hinz, P., Hofmann, K., Leisenring, J., , Males, J., et al. (2013, jul). A 100-Night Exoplanet Imaging Survey at the LBT. In Protostars and Planets VI Posters, 6.
• ampAacute, ., Brah 'am, P., Mo 'or, A., Apai, D., Balog, Z., Grady, C., Henning, T., Juh 'asz, A., Kiss, C., 'al, a., ., ., Pascucci, I., J., S., & Vavrek, R. (2012, mar). Spatially resolved far-infrared imaging of bright debris disks: studying the disk structure and the stirring mechanism. In From Atoms to Pebbles: Herschel's view of Star and Planet Formation.

Presentations

• Apai, D. (2017, All). Presentations (23 talks, including 5 invited talks and 5 colloquia). Various international conferences and institutions.
• 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).
  More info

  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.
• Apai, D. (2015, April). Earths in Other Solar Systems. Steward Observatory Journal Club. Tucson, Arizona: Steward Observatory.
• Apai, D. (2015, April). Extrasolar Storms: Cloud Cover and Atmospheric Dynamics in Brown Dwarfs and Exoplanets. Invited Review Talk at Hubble Space Telescope 25th Anniversary Symposium. Baltimore, MD: Space Telescope Science Institute.
• Apai, D. (2015, Aug). Mapping Silicate Storms in Brown Dwarfs and Exoplanets. Steward Internal Symposium. Tucson, Arizona: Steward Observatory.
• Apai, D. (2015, July). Earths In Other Solar Systems: The Formation of Habitable Zone Earth-Like Planets With Biocritical Ingredients. Pathways toward Habitable Planets II. Bern, Switzerland: International Conference.
• Apai, D. (2015, July). Extrasolar Storms: Cloud Cover and Atmospheric Dynamics in Brown Dwarfs and Exoplanets. Seminar at MPIA Heidelberg. Heidelberg, Germany: Max Planck Institute for Astronomy.
• Apai, D. (2015, July). Mapping Silicate Storms. Pathways toward Habitable Planets II. Bern, Switzerland: International Conference.
• Apai, D. (2015, July). Summary of Splinter Session: Mapping Other Worlds. Pathways toward Habitable Planets II. Bern, Switzerland: International Conference.
• Apai, D. (2015, June). Extrasolar Storms: Cloud Cover and Atmospheric Dynamics in Brown Dwarfs and Exoplanets. Seminar at the Institute for Theoretical Astrophysics. Heidelberg, Germany: University of Heidelberg.
• Apai, D. (2015, March). Extrasolar Storms: Mapping Cloud Cover and Atmospheric Dynamics in Brown Dwarfs and Exoplanets. FLASH Seminars, Steward/NOAO. Tucson, Arizona.
• Apai, D. (2015, May). Exo-S and Exo-C Science and Technology Design Team Reports. LPL Journal Club. Tucson, Arizona: Lunar and Planetary Laboratory.
• Apai, D. (2015, Oct). EXOPAG and NExSS. Steward Observatory Journal Club. Tucson, Arizona: Steward Observatory.
• Apai, D. (2015, Oct). Earths In Other Solar Systems: The Formation of Habitable Zone Earth-Like Planets With Biocritical Ingredients. Molecular & Cellular Biology Joint Seminar Series. Tucson, Arizona: Molecular and Cellular Biology Department.
• Apai, D. (2015, Sep). EXOPAG, EOS, & UA ARC. UA Astronomy Strategic Meeting with VPR. Tucson, Arizona: Steward Observatory.
• Apai, D. (2015, Sep). Earths In Other Solar Systems: The Formation of Habitable Zone Earth-Like Planets With Biocritical Ingredients. Colloquium, Arizona State University. Phoenix, Arizona: ASU.
• Apai, D. (2015, Sep). Extrasolar Storms in High Defintion: Cloud Physics and Atmospheric Dynamics in Exoplanets. ATLAST/HDST Seminar Series of the Goddard Space Flight Center. Goddard Space Flight Center (remote presentation): NASA GSFC.
• Apai, D. (2015, Sep). Extrasolar Storms: Cloud Cover and Atmospheric Dynamics in Brown Dwarfs and Exoplanets. Research Seminar, Arizona State University. Phoenix, Arizona: ASU.
• Apai, D. (2014, 01). Extrasolar Storms: Mapping Clouds in Brown Dwarfs and Exoplanets!. American Astronomical Society Meeting / Special Session. Washington DC: NASA.
• Apai, D. (2014, 02). Exploring Clouds and Atmospheric Dynamics in Brown Dwarfs and Extrasolar Giant Planets. Colloquium. Lunar and Planetary Laboratory.
• Apai, D. (2014, 02). The Brown Dwarf - Exoplanet Connection. Exoclimes 2014 Conference. Davos, Switzerland: NASA + Conference.
• Apai, D. (2014, 06). Disk Structure and Disk-Planet Interactions in the Beta Pictoris System. Institute Seminar. Konkoly Observatory, Hungary: NASA.
• Apai, D. (2014, 06). Extrasolar Storms: Mapping Clouds in Brown Dwarfs and Exoplanets!. Cool Stars 18 Conference. Flagstaff, AZ: NASA.
• Apai, D. (2014, 06). Extrasolar Storms: Mapping Clouds in Brown Dwarfs and Exoplanets!. Seminar. Institute of Astronomy, Cambridge University: NASA + Cambridge University.
• Apai, D. (2014, 06). Extrasolar Storms: Mapping Clouds in Brown Dwarfs and Exoplanets. Institute Seminar. University College London.
• Apai, D. (2014, 06). Extrasolar Storms: Mapping Clouds in Brown Dwarfs and Exoplanets. Seminar. Exeter University.
• Apai, D. (2014, 09). The Disk Structure and the Planet in the Beta Pictoris System!. Beta Pic at 30, Paris. Paris: Conference / ESO.
• Apai, D. (2014, 12). Extrasolar Storms: Cloud Structure and Atmospheric Dynamics in Brown Dwarfs and Exoplanets. Colloquoium. Univ. Colorado, Boulder: Univ. Colorado.

Poster Presentations

• Kim, J. S., Fang, M., Pascucci, I., & Apai, D. (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.

Reviews

• Graves, L. R., Smith, G. A., Apai, D., & Kim, D. W. (2019. Precision Optics Manufacturing and Control for Next-Generation Large Telescopes(pp 65-90). Nanomanufacturing and Metrology.

Case Studies

• Turnbull, M., Showman, A. P., Schneider, G., Roberge, A., Plavchan, P., Pascucci, I., Moore, W., McElwain, M., Madhusudhan, N., Lowrance, P., Kastings, J., Iro, N., Ford, E., Danchi, W., Crossfield, I., Breckinridge, J., Boss, A., Barman, T., Domagal-Goldman, S., , Mandell, A., et al. (2017. Exploring Other Worlds: Science Questions for Future Direct Imaging Missions (SAG 15)(p. 99).

Others

• Mulders, G. D., Pascucci, I., Apai, D., & Ciesla, F. J. (2019). EPOS: Exoplanet Population Observation Simulator.