TOI-431/HIP 26013: a super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet

Osborn, Ares and Armstrong, David J. and Cale, Bryson and Brahm, Rafael and Wittenmyer, Robert A. and Dai, Fei and Crossfield, Ian J. M. and Bryant, Edward M. and Adibekyan, Vardan and Cloutier, Ryan and Collins, Karen A. and Mena, E. Delgado and Fridlund, Malcolm and Hellier, Coel and Howell, Steve B. and King, George W. and Lillo-Box, Jorge and Otegi, Jon and Sousa, S. and Stassun, Keivan G. and Matthews, Elisabeth C. and Ziegler, Carl and Ricker, George and Vanderspek, Roland and Latham, David W. and Seager, S. and Winn, Joshua N. and Jenkins, Jon M. and Acton, Jack S. and Addison, Brett C. ORCID: and Anderson, David R. and Ballard, Sarah and Barrado, David and Barros, Susana C. C. and Batalha, Natalie and Bayliss, Daniel and Barclay, Thomas and Benneke, Bjorn and Berberian, John and Bouchy, Francois and Bowler, Brendan P. and Briceno, Cesar and Burke, Christopher J. and Burleigh, Matthew R. and Casewell, Sarah L. and Ciardi, David and Collins, Kevin I. and Cooke, Benjamin F. and Demangeon, Olivier D. S. and Diaz, Rodrigo F. and Dorn, C. and Dragomir, Diana and Dressing, Courtney and Dumusque, Xavier and Espinoza, Nestor and Figueira, P. and Fulton, Benjamin and Furlan, E. and Gaidos, E. and Geneser, C. and Gill, Samuel and Goad, Michael R. and Gonzales, Erica J. and Gorjian, Varoujan and Gunther, Maximilian N. and Helled, Ravit and Henderson, Beth A. and Henning, Thomas and Hogan, Aleisha and Hojjatpanah, Saeed and Horner, Jonathan and Howard, Andrew W. and Hoyer, Sergio and Huber, Dan and Isaacson, Howard and Jenkins, James S. and Jensen, Eric L. N. and Jordan, Andres and Kane, Stephen R. and Kidwell, Richard C. and Kielkopf, John and Law, Nicholas and Lendl, Monika and Lund, M. and Matson, Rachel A. and Mann, Andrew W. and McCormac, James and Mengel, Matthew W. ORCID: and Morales, Farisa Y. and Nielsen, Louise D. and Okumura, Jack and Osborn, Hugh P. and Petigura, Erik A. and Plavchan, Peter and Pollacco, Don and Quintana, Elisa V. and Raynard, Liam and Robertson, Paul and Rose, Mark E. and Roy, Arpita and Reefe, Michael and Santerne, Alexandre and Santos, Nuno C. and Sarkis, Paula and Schlieder, J. and Schwarz, Richard P. and Scott, Nicholas J. and Shporer, Avi and Smith, A. M. S. and Stibbard, C. and Stockdale, Chris and Strom, Paul A. and Twicken, Joseph D. and Tan, Thiam-Guan and Tanner, A. and Teske, J. and Tilbrook, Rosanna H. and Tinney, C. G. and Udry, Stephane and Villasenor, Jesus Noel and Vines, Jose I. and Wang, Sharon X. and Weiss, Lauren M. and West, Richard G. and Wheatley, Peter J. and Wright, Duncan J. and Zhang, Hui and Zohrabi, F. (2021) TOI-431/HIP 26013: a super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet. Monthly Notices of the Royal Astronomical Society, 507 (2). pp. 2782-2803. ISSN 0035-8711

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We present the bright (V-mag = 9.12), multiplanet system TOI-431, characterized with photometry and radial velocities (RVs). We estimate the stellar rotation period to be 30.5 +/- 0.7 d using archival photometry and RVs. Transiting Exoplanet Survey Satellite (TESS) objects of Interest (TOI)-431b is a super-Earth with a period of 0.49 d, a radius of 1.28 +/- 0.04 R-circle plus, a mass of 3.07 +/- 0.35 M-circle plus, and a density of 8.0 +/- 1.0 g cm(-3); TOI-431 d is a sub-Neptune with a period of 12.46 d, a radius of 3.29 +/- 0.09 R-circle plus, a mass of M-circle plus, and a density of 1.36 +/- 0.25 g cm(-3). We find a third planet, TOI-431c, in the High Accuracy Radial velocity Planet Searcher RV data, but it is not seen to transit in the TESS light curves. It has an Msin i of M-circle plus, and a period of 4.85 d. TOI-431d likely has an extended atmosphere and is one of the most well-suited TESS discoveries for atmospheric characterization, while the super-Earth TOI-431b may be a stripped core. These planets straddle the radius gap, presenting an interesting case-study for atmospheric evolution, and TOI-431b is a prime TESS discovery for the study of rocky planet phase curves.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Astrophysics (1 Aug 2018 -)
Date Deposited: 11 Jan 2022 00:31
Last Modified: 14 Jan 2022 00:54
Uncontrolled Keywords: planets and satellites: detection; planets and satellites:; fundamental parameters; planets and satellites: individual: (TOI-431; TIC 31374837); Astrophysics - Earth and Planetary Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
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