Physical Sciences and Mathematics Commons^™

From Thermal Dissociation To Condensation In The Atmospheres Of Ultra Hot Jupiters: Wasp-121b In Context, Vivien Parmentier, Mike R. Line, Jacob L. Bean, Megan Mansfield, Laura Kreidberg, Roxana Lupu, Channon Visscher, Jean-Michel Desert, Jonathan J. Fortney, Magalie Deleuil, Jacob Arcangeli, Adam P. Showman, Mark S. Marley

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Context. A new class of exoplanets has emerged: the ultra hot Jupiters, the hottest close-in gas giants. The majority of them have weaker-than-expected spectral features in the 1.1−1.7 μm bandpass probed by HST/WFC3 but stronger spectral features at longer wavelengths probed by Spitzer. This led previous authors to puzzling conclusions about the thermal structures and chemical abundances of these planets.

Aims. We investigate how thermal dissociation, ionization, H− opacity, and clouds shape the thermal structures and spectral properties of ultra hot Jupiters.

Methods. We use the SPARC/MITgcm to model the atmospheres of four ultra hot Jupiters and discuss …

An L Band Spectrum Of The Coldest Brown Dwarf, Caroline V. Morley, Andrew J. Skemer, Katelyn N. Allers, Mark S. Marley, Jacqueline K. Faherty, Channon Visscher, Samuel A. Beiler, Brittany E. Miles, Roxana Lupu, Richard S. Freedman, Jonathan J. Fortney, Thomas R. Geballe, Gordon L. Bjoraker

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The coldest brown dwarf, WISE 0855, is the closest known planetary-mass, free-floating object and has a temperature nearly as cold as the solar system gas giants. Like Jupiter, it is predicted to have an atmosphere rich in methane, water, and ammonia, with clouds of volatile ices. WISE 0855 is faint at near-infrared wavelengths and emits almost all its energy in the mid-infrared. Skemer et al. (2016) presented a spectrum of WISE 0855 from 4.5–5.1 µm (M band), revealing water vapor features. Here, we present a spectrum of WISE 0855 in L band, from 3.4–4.14 µm. We present a set of …

Retrieval Of Atmospheric Properties Of Cloudy L Dwarfs, Ben Burningham, M. S. Marley, M. R. Line, R. Lupu, Channon Visscher, C. V. Morley, D. Saumon, R. Freedman

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We present the first results from applying the spectral inversion technique in the cloudy L dwarf regime. Our new framework provides a flexible approach to modelling cloud opacity which can be built incrementally as the data require and improves upon previous retrieval experiments in the brown dwarf regime by allowing for scattering in two-stream radiative transfer. Our first application of the tool to two mid-L dwarfs is able to reproduce their near-infrared spectra far more closely than grid models. Our retrieved thermal, chemical and cloud profiles allow us to estimate Teff=1796−25+23" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; …

High Temperature Condensate Clouds In Super-Hot Jupiter Atmospheres, H. R. Wakeford, Channon Visscher, Nikole K. Lewis, Avi M. Mandell

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Deciphering the role of clouds is central to our understanding of exoplanet atmo- spheres, as they have a direct impact on the temperature and pressure structure, and observational properties of the planet. Super-hot Jupiters occupy a temperature regime similar to low mass M-dwarfs, where minimal cloud condensation is expected. However, observations of exoplanets such as WASP-12b (Teq∼2500 K) result in a transmission spectrum indicative of a cloudy atmosphere. We re-examine the temperature and pressure space occupied by these super-hot Jupiter atmospheres, to explore the role of the initial Al- and Ti-bearing condensates as the main source of cloud material. Due …

On The Composition Of Young, Directly Imaged Giant Planets, Julianne I. Moses, Mark S. Marley, K. Zahnle, M. R. Line, Jonathan J. Fortney, T. S. Barman, Channon Visscher, Nikole K. Lewis, M. J. Wolff

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The past decade has seen significant progress on the direct detection and characterization of young, self-luminous giant planets at wide orbital separations from their host stars. Some of these planets show evidence for disequilibrium processes like transport-induced quenching in their atmospheres; photochemistry may also be important, despite the large orbital distances. These disequilibrium chemical processes can alter the expected composition, spectral behavior, thermal structure, and cooling history of the planets, and can potentially confuse determinations of bulk elemental ratios, which provide important insights into planet-formation mechanisms. Using a thermo/photochemical kinetics and transport model, we investigate the extent to which disequilibrium …

Hunt For Planet Nine: Atmosphere, Spectra, Evolution, And Detectability, Jonathan J. Fortney, Mark S. Marley, Gregory Laughlin, Nadine Nettelmann, Caroline V. Morley, Roxana E. Lupu, Channon Visscher, Pavle Jeremic, Wade G. Khadder, Mason Hargrave

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We investigate the physical characteristics of the solar system's proposed Planet Nine using modeling tools with a heritage of studying Uranus and Neptune. For a range of plausible masses and interior structures, we find upper limits on the intrinsic , from ~35 to 50 K for masses of 5–20 M _⊕, and we also explore lower values. Possible planetary radii could readily span from 2.7 to 6 R _⊕, depending on the mass fraction of any H/He envelope. Given its cold atmospheric temperatures, the planet encounters significant methane condensation, which dramatically alters the atmosphere away from simple Neptune-like …

Leech Exoplanet Imaging Survey: Characterization Of The Coldest Directly Imaged Exoplanet, Gj 504 B, And Evidence For Super-Stellar Metallicity, Andrew J. Skemer, Caroline V. Morley, Neil T. Zimmerman, Michael F. Skrutskie, Jarron Leisenring, Esther Buenzli, Mickael Bonnefoy, Vanessa Bailey, Philip Hinz, Denis Defrere, Simone Esposito, Daniel Apai, Beth Biller, Wolfgang Brandner, Laird Close, Justin R. Crepp, Robert J. De Rosa, Silvano Desidera, Josh Eisner, Jonathan Fortney, Richard Freedman, Thomas Henning, Karl-Heinz Hofmann, Taisiya Kopytova, Roxana Lupu, Anne-Lise Maire, Jared R. Males, Mark Marley, Katie Morzinski, Apurva Oza, Jenny Patience, Abhijith Rajan, George Rieke, Dieter Schertl, Joshua Schlieder, Jordan Stone, Kate Su, Amali Vaz, Channon Visscher, Kimberly Ward-Duong, Gerd Weigelt, Charles E. Woodward

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As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly-imaged exoplanets were all L-type. Recently, Kuzuhara et al. (2013) announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ∼500 K temperature that bridges the …