Planetary Climate Dynamics

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Modeling Polarization Signals from Cloudy Brown Dwarfs Luhman 16 A and B in Three Dimensions

The Astrophysical Journal American Astronomical Society 923:1 (2021) 113

Authors:

Sagnick Mukherjee, Jonathan J Fortney, Rebecca Jensen-Clem, Xianyu Tan, Mark S Marley, Natasha E Batalha

New Evidence for Wet Accretion of Inner Solar System Planetesimals from Meteorites Chelyabinsk and Benenitra

The Planetary Science Journal American Astronomical Society 2:6 (2021) 244

Authors:

Ziliang Jin, Maitrayee Bose, Tim Lichtenberg, Gijs D Mulders

TOI-2109: An Ultrahot Gas Giant on a 16 hr Orbit

The Astronomical Journal American Astronomical Society 162:6 (2021) 256

Authors:

Ian Wong, Avi Shporer, George Zhou, Daniel Kitzmann, Thaddeus D Komacek, Xianyu Tan, Ren茅 Tronsgaard, Lars A Buchhave, Shreyas Vissapragada, Michael Greklek-McKeon, Joseph E Rodriguez, John P Ahlers, Samuel N Quinn, Elise Furlan, Steve B Howell, Allyson Bieryla, Kevin Heng, Heather A Knutson, Karen A Collins, Kim K McLeod, Perry Berlind, Peyton Brown, Michael L Calkins, Jerome P de Leon, Emma Esparza-Borges, Gilbert A Esquerdo, Akihiko Fukui, Tianjun Gan, Eric Girardin, Crystal L Gnilka, Masahiro Ikoma, Eric LN Jensen, John Kielkopf, Takanori Kodama, Seiya Kurita, Kathryn V Lester, Pablo Lewin, Giuseppe Marino, Felipe Murgas, Norio Narita, Enric Pall茅, Richard P Schwarz, Keivan G Stassun, Motohide Tamura, Noriharu Watanabe, Bj枚rn Benneke, George R Ricker, David W Latham, Roland Vanderspek, Sara Seager, Joshua N Winn, Jon M Jenkins, Douglas A Caldwell, William Fong, Chelsea X Huang, Ismael Mireles, Joshua E Schlieder, Bernie Shiao, Jesus Noel Villase帽or

Convection modeling of pure-steam atmospheres

ArXiv 2111.15265 (2021)

Authors:

Xianyu Tan, Maxence Lefevre, Raymond Pierrehumbert

Inferring shallow surfaces on sub-neptune exoplanets with JWST

The Astrophysical Journal Letters IOP Publishing 922:2 (2021) L27

Authors:

Shang-Min Tsai, Hamish Innes, Tim Lichtenberg, Jake Taylor, Matej Malik, Katy Chubb, Raymond Pierrehumbert

Abstract:

Planets smaller than Neptune and larger than Earth make up the majority of the discovered exoplanets. Those with H2-rich atmospheres are prime targets for atmospheric characterization. The transition between the two main classes, super-Earths and sub-Neptunes, is not clearly understood as the rocky surface is likely not accessible to observations. Tracking several trace gases (specifically the loss of ammonia (NH3) and hydrogen cyanide (HCN)) has been proposed as a proxy for the presence of a shallow surface. In this work, we revisit the proposed mechanism of nitrogen conversion in detail and find its timescale on the order of a million years. NH3 exhibits dual paths converting to N2 or HCN, depending on the UV radiation of the star and the stage of the system. In addition, methanol (CH3OH) is identified as a robust and complementary proxy for a shallow surface. We follow the fiducial example of K2-18b with a 2D photochemical model on an equatorial plane. We find a fairly uniform composition distribution below 0.1 mbar controlled by the dayside, as a result of slow chemical evolution. NH3 and CH3OH are concluded to be the most unambiguous proxies to infer surfaces on sub-Neptunes in the era of the James Webb Space Telescope.