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

Ares Osborn*, David J. Armstrong, Bryson Cale, Rafael Brahm, Robert A. Wittenmyer, Fei Dai, Ian J.M. Crossfield, Edward M. Bryant, Vardan Adibekyan, Ryan Cloutier, Karen A. Collins, E. Delgado Mena, Malcolm Fridlund, Coel Hellier, Steve B. Howell, George W. King, Jorge Lillo-Box, Jon Otegi, S. Sousa, Keivan G. StassunElisabeth C. Matthews, Carl Ziegler, George Ricker, Roland Vanderspek, David W. Latham, S. Seager, Joshua N. Winn, Jon M. Jenkins, Jack S. Acton, Brett C. Addison, David R. Anderson, Sarah Ballard, David Barrado, Susana C.C. Barros, Natalie Batalha, Daniel Bayliss, Thomas Barclay, Björn Benneke, John Berberian, Francois Bouchy, Brendan P. Bowler, César Briceño, Christopher J. Burke, Matthew R. Burleigh, Sarah L. Casewell, David Ciardi, Kevin I. Collins, Benjamin F. Cooke, Olivier D.S. Demangeon, Rodrigo F. Díaz, C. Dorn, Diana Dragomir, Courtney Dressing, Xavier Dumusque, Néstor Espinoza, P. Figueira, Benjamin Fulton, E. Furlan, E. Gaidos, C. Geneser, Samuel Gill, Michael R. Goad, Erica J. Gonzales, Varoujan Gorjian, Maximilian N. Günther, Ravit Helled, Beth A. Henderson, Thomas Henning, Aleisha Hogan, Saeed Hojjatpanah, Jonathan Horner, Andrew W. Howard, Sergio Hoyer, Dan Huber, Howard Isaacson, James S. Jenkins, Eric L.N. Jensen, Andrés Jordán, Stephen R. Kane, Richard C. Kidwell, John Kielkopf, Nicholas Law, Monika Lendl, M. Lund, Rachel A. Matson, Andrew W. Mann, James McCormac, Matthew W. Mengel, Farisa Y. Morales, Louise D. Nielsen, Jack Okumura, Hugh P. Osborn, Erik A. Petigura, Peter Plavchan, Don Pollacco, Elisa V. Quintana, Liam Raynard, Paul Robertson, Mark E. Rose, Arpita Roy, Michael Reefe, Alexandre Santerne, Nuno C. Santos, Paula Sarkis, J. Schlieder, Richard P. Schwarz, Nicholas J. Scott, Avi Shporer, A. M.S. Smith, C. Stibbard, Chris Stockdale, Paul A. Strøm, Joseph D. Twicken, Thiam Guan Tan, A. Tanner, J. Teske, Rosanna H. Tilbrook, C. G. Tinney, Stephane Udry, Jesus Noel Villaseñor, Jose I. Vines, Sharon X. Wang, Lauren M. Weiss, Richard G. West, Peter J. Wheatley, Duncan J. Wright, Hui Zhang, F. Zohrabi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We present the bright (Vmag = 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)-431 b is a super-Earth with a period of 0.49 d, a radius of 1.28 ± 0.04 R, a mass of 3.07 ± 0.35 M, 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, a mass of 9.90+1.53-1.49 M, and a density of 1.36 ± 0.25 g cm-3. We find a third planet, TOI-431 c, 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 2.83+0.41-0.34 M, and a period of 4.85 d. TOI-431 d likely has an extended atmosphere and is one of the most well-suited TESS discoveries for atmospheric characterization, while the super-Earth TOI-431 b may be a stripped core. These planets straddle the radius gap, presenting an interesting case-study for atmospheric evolution, and TOI-431 b is a prime TESS discovery for the study of rocky planet phase curves.

Original languageEnglish
Pages (from-to)2782-2803
Number of pages22
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - 1 Oct 2021
Externally publishedYes


  • planets and satellites: detection
  • planets and satellites: fundamental parameters
  • planets and satellites: individual: (TOI-431, TIC 31374837)


Dive into the research topics of 'TOI-431/HIP 26013: A super-Earth and a sub-Neptune transiting a bright, early K dwarf, with a third RV planet'. Together they form a unique fingerprint.

Cite this