TOI-199 b: A Well-characterized 100 day Transiting Warm Giant Planet with TTVs Seen from Antarctica

Melissa J. Hobson, Trifon Trifonov, Thomas Henning, Andrés Jordán, Felipe Rojas, Nestor Espinoza, Rafael Brahm, Jan Eberhardt, Matías I. Jones, Djamel Mekarnia, Diana Kossakowski, Martin Schlecker, Marcelo Tala Pinto, Pascal José Torres Miranda, Lyu Abe, Khalid Barkaoui, Philippe Bendjoya, François Bouchy, Marco Buttu, Ilaria CarleoKaren A. Collins, Knicole D. Colón, Nicolas Crouzet, Diana Dragomir, Georgina Dransfield, Thomas Gasparetto, Robert F. Goeke, Tristan Guillot, Maximilian N. Günther, Saburo Howard, Jon M. Jenkins, Judith Korth, David W. Latham, Monika Lendl, Jack J. Lissauer, Christopher R. Mann, Ismael Mireles, George R. Ricker, Sophie Saesen, Richard P. Schwarz, S. Seager, Ramotholo Sefako, Avi Shporer, Chris Stockdale, Olga Suarez, Thiam Guan Tan, Amaury H.M. Amaury, Solène Ulmer-Moll, Roland Vanderspek, Joshua N. Winn, Bill Wohler, George Zhou

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


We present the spectroscopic confirmation and precise mass measurement of the warm giant planet TOI-199 b. This planet was first identified in TESS photometry and confirmed using ground-based photometry from ASTEP in Antarctica including a full 6.5 hr long transit, PEST, Hazelwood, and LCO; space photometry from NEOSSat; and radial velocities (RVs) from FEROS, HARPS, CORALIE, and CHIRON. Orbiting a late G-type star, TOI-199 b has a 104.854 − 0.002 + 0.001 day period, a mass of 0.17 ± 0.02 M J, and a radius of 0.810 ± 0.005 R J. It is the first warm exo-Saturn with a precisely determined mass and radius. The TESS and ASTEP transits show strong transit timing variations (TTVs), pointing to the existence of a second planet in the system. The joint analysis of the RVs and TTVs provides a unique solution for the nontransiting companion TOI-199 c, which has a period of 273.69 − 0.22 + 0.26 days and an estimated mass of 0.28 − 0.01 + 0.02 M J . This period places it within the conservative habitable zone.

Original languageEnglish (US)
Article number201
JournalAstronomical Journal
Issue number5
StatePublished - Nov 1 2023

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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