Exoplanets and Stellar Physics

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Hot planets around cool stars – two short-period mini-Neptunes transiting the late K-dwarf TOI-1260

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 505:4 (2021) 4684-4701

Authors:

IY Georgieva, CM Persson, O Barragán, G Nowak, M Fridlund, D Locci, E Palle, R Luque, I Carleo, D Gandolfi, SR Kane, J Korth, KG Stassun, J Livingston, EC Matthews, KA Collins, SB Howell, LM Serrano, S Albrecht, A Bieryla, CE Brasseur, D Ciardi, WD Cochran, KD Colon, IJM Crossfield, Sz Csizmadia, HJ Deeg, M Esposito, E Furlan, T Gan, E Goffo, E Gonzales, S Grziwa, EW Guenther, P Guerra, T Hirano, JM Jenkins, ELN Jensen, P Kabáth, E Knudstrup, KWF Lam, DW Latham, AM Levine, RA Matson, S McDermott, HLM Osborne, M Paegert, SN Quinn, S Redfield, GR Ricker, JE Schlieder, NJ Scott, S Seager, AMS Smith, P Tenenbaum, JD Twicken, R Vanderspek, V Van Eylen, JN Winn
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TOI-220 b: a warm sub-Neptune discovered by TESS

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 505:3 (2021) 3361-3379

Authors:

S Hoyer, D Gandolfi, DJ Armstrong, M Deleuil, L Acuña, JR de Medeiros, E Goffo, J Lillo-Box, E Delgado Mena, TA Lopez, A Santerne, S Sousa, M Fridlund, V Adibekyan, KA Collins, LM Serrano, P Cortés-Zuleta, SB Howell, H Deeg, A Aguichine, O Barragán, EM Bryant, BL Canto Martins, KI Collins, BF Cooke, RF Díaz, M Esposito, E Furlan, S Hojjatpanah, J Jackman, JM Jenkins, ELN Jensen, DW Latham, IC Leão, RA Matson, LD Nielsen, A Osborn, JF Otegi, F Rodler, S Sabotta, NJ Scott, S Seager, C Stockdale, PA Strøm, R Vanderspek, V Van Eylen, PJ Wheatley, JN Winn, JM Almenara, D Barrado, SCC Barros, D Bayliss, F Bouchy, PT Boyd, J Cabrera, WD Cochran, O Demangeon, JP Doty, X Dumusque, P Figueira, W Fong, S Grziwa, AP Hatzes, P Kabáth, E Knudstrup, J Korth, JH Livingston, R Luque, O Mousis, SE Mullally, HP Osborn, E Pallé, CM Persson, S Redfield, NC Santos, J Smith, J Šubjak, JD Twicken, S Udry, DA Yahalomi
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Planet Hunters TESS III: two transiting planets around the bright G dwarf HD 152843

(2021)

Authors:

Nora L Eisner, Belinda A Nicholson, Oscar Barragán, Suzanne Aigrain, Chris Lintott, Laurel Kaye, Baptiste Klein, Grant Miller, Jake Taylor, Norbert Zicher, Lars A Buchhave, Douglas A Caldwell, Jonti Horner, Joe Llama, Annelies Mortier, Vinesh M Rajpaul, Keivan Stassun, Avi Sporer, Andrew Tkachenko, Jon M Jenkins, David W Latham, George R Ricker, Sara Seager, Joshua N Winn, Safaa Alhassan, Elisabeth ML Baeten, Stewart J Bean, David M Bundy, Vitaly Efremov, Richard Ferstenou, Brian L Goodwin, Michelle Hof, Tony Hoffman, Alexander Hubert, Lily Lau, Sam Lee, David Maetschke, Klaus Peltsch, Cesar Rubio-Alfaro, Gary M Wilson
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Planet Hunters TESS III: two transiting planets around the bright G dwarf HD 152843

Monthly Notices of the Royal Astronomical Society, Volume 505, Issue 2, August 2021, Pages 1827–1840

Authors:

N L Eisner, B A Nicholson, O Barragán, S Aigrain, C Lintott, L Kaye, B Klein, G Miller, J Taylor, N Zicher, L A Buchhave, D A Caldwell, J Horner, J Llama, A Mortier, V M Rajpaul, K Stassun, A Sporer, A Tkachenko, J M Jenkins, D Latham, G Ricker, S Seager, J Winn, S Alhassan, E M L Baeten, S J Bean, D M Bundy, V Efremov, R Ferstenou, B L Goodwin, M Hof, T Hoffman, A Hubert, L Lau, S Lee, D Maetschke, K Peltsch, C Rubio-Alfaro, G M Wilson

Abstract:

We report on the discovery and validation of a two-planet system around a bright (V = 8.85 mag) early G dwarf (1.43  R⊙, 1.15  M⊙, TOI 2319) using data from NASA’s Transiting Exoplanet Survey Satellite (TESS). Three transit events from two planets were detected by citizen scientists in the month-long TESS light curve (sector 25), as part of the Planet Hunters TESS project. Modelling of the transits yields an orbital period of 11.6264+0.0022−0.0025 d and radius of 3.41+0.14−0.12 R⊕ for the inner planet, and a period in the range 19.26–35 d and a radius of 5.83+0.14−0.14 R⊕ for the outer planet, which was only seen to transit once. Each signal was independently statistically validated, taking into consideration the TESS light curve as well as the ground-based spectroscopic follow-up observations. Radial velocities from HARPS-N and EXPRES yield a tentative detection of planet b, whose mass we estimate to be 11.56+6.58−6.14 M⊕, and allow us to place an upper limit of 27.5 M⊕ (99 per cent confidence) on the mass of planet c. Due to the brightness of the host star and the strong likelihood of an extended H/He atmosphere on both planets, this system offers excellent prospects for atmospheric characterization and comparative planetology.
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Redox hysteresis of super-Earth exoplanets from magma ocean circulation

Astrophysical Journal Letters American Astronomical Society 914:1 (2021) L4

Abstract:

Internal redox reactions may irreversibly alter the mantle composition and volatile inventory of terrestrial and super-Earth exoplanets and affect the prospects for atmospheric observations. The global efficacy of these mechanisms, however, hinges on the transfer of reduced iron from the molten silicate mantle to the metal core. Scaling analysis indicates that turbulent diffusion in the internal magma oceans of sub-Neptunes can kinetically entrain liquid iron droplets and quench core formation. This suggests that the chemical equilibration between core, mantle, and atmosphere may be energetically limited by convective overturn in the magma flow. Hence, molten super-Earths possibly retain a compositional memory of their accretion path. Redox control by magma ocean circulation is positively correlated with planetary heat flow, internal gravity, and planet size. The presence and speciation of remanent atmospheres, surface mineralogy, and core mass fraction of primary envelope-stripped exoplanets may thus constrain magma ocean dynamics.
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