TOI-733 b: A planet in the small-planet radius valley orbiting a Sun-like star

Iskra Y. Georgieva, Carina M. Persson, Elisa Goffo, Lorena Acuña, Artyom Aguichine, Luisa M. Serrano, Kristine W.F. Lam, Davide Gandolfi, Karen A. Collins, Steven B. Howell, Fei Dai, Malcolm Fridlund, Judith Korth, Magali Deleuil, Oscar Barragán, William D. Cochran, Szilárd Csizmadia, Hans J. Deeg, Eike Guenther, Artie P. HatzesJon M. Jenkins, John Livingston, Rafael Luque, Olivier Mousis, Hannah L.M. Osborne, Enric Palle, Seth Redfield, Vincent Van Eylen, Joseph D. Twicken, Joshua N. Winn, Ahlam Alqasim, Kevin I. Collins, Crystal L. Gnilka, David W. Latham, Hannah M. Lewis, Howard M. Relles, George R. Ricker, Pamela Rowden, Sara Seager, Avi Shporer, Thiam Guan Tan, Andrew Vanderburg, Roland Vanderspek

Research output: Contribution to journalArticlepeer-review


We report the discovery of a hot (Teq ≈ 1055 K) planet in the small-planet radius valley that transits the Sun-like star TOI-733. It was discovered as part of the KESPRINT follow-up program of TESS planets carried out with the HARPS spectrograph. TESS photometry from sectors 9 and 36 yields an orbital period of {equation presented} days and a radius of {equation presented}. Multi-dimensional Gaussian process modelling of the radial velocity measurements from HARPS and activity indicators gives a semi-amplitude of K = 2.23 ± 0.26 m s-1, translating into a planet mass of {equation presented}. These parameters imply that the planet is of moderate density ({equation presented}) and place it in the transition region between rocky and volatile-rich planets with H/He-dominated envelopes on the mass-radius diagram. Combining these with stellar parameters and abundances, we calculated planet interior and atmosphere models, which in turn suggest that TOI-733 b has a volatile-enriched, most likely secondary outer envelope, and may represent a highly irradiated ocean world. This is one of only a few such planets around G-type stars that are well characterised.

Original languageEnglish (US)
Article numberA117
JournalAstronomy and Astrophysics
StatePublished - Jun 1 2023

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planets and satellites: composition
  • Planets and satellites: detection
  • Planets and satellites: individual: TOI-733
  • Techniques: photometric
  • Techniques: radial velocities


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