TOI-222: A single-transit TESS candidate revealed to be a 34-d eclipsing binary with CORALIE, EulerCam, and NGTS

Monika Lendl, François Bouchy, Samuel Gill, Louise D. Nielsen, Oliver Turner, Keivan Stassun, Jack S. Acton, David R. Anderson, David J. Armstrong, Daniel Bayliss, Claudia Belardi, Edward M. Bryant, Matthew R. Burleigh, Alexander Chaushev, Sarah L. Casewell, Benjamin F. Cooke, Philipp Eigmüller, Edward Gillen, Michael R. Goad, Maximilian N. GüntherJanis Hagelberg, James S. Jenkins, Tom Louden, Maxime Marmier, James McCormac, Maximiliano Moyano, Don Pollacco, Liam Raynard, Rosanna H. Tilbrook, Stéphane Udry, Jose I. Vines, Richard G. West, Peter J. Wheatley, George Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Josh Winn, Jon M. Jenkins, Brett Addison, César Briceño, Rafael Brahm, Douglas A. Caldwell, John Doty, Néstor Espinoza, Bob Goeke, Thomas Henning, Andrés Jordán, Akshata Krishnamurthy, Nicholas Law, Robert Morris, Jack Okumura, Andrew W. Mann, Joseph E. Rodriguez, Paula Sarkis, Joshua Schlieder, Joseph D. Twicken, Steven Villanueva, Robert A. Wittenmyer, Duncan J. Wright, Carl Ziegler

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


We report the period, eccentricity, and mass determination for the Transiting Exoplanet Survey Satellite (TESS) single-transit event candidate TOI-222, which displayed a single 3000 ppm transit in the TESS 2-min cadence data from Sector 2. We determine the orbital period via radial velocity measurements (P = 33.9 d), which allowed for ground-based photometric detection of two subsequent transits. Our data show that the companion to TOI-222 is a low-mass star, with a radius of 0.18+003910 R and a mass of 0.23 ± 0.01 M. This discovery showcases the ability to efficiently discover long-period systems from TESS single-transit events using a combination of radial velocity monitoring coupled with high-precision ground-based photometry.

Original languageEnglish (US)
Pages (from-to)1761-1769
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Feb 1 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planetary systems
  • Stars: individual: TOI-222
  • Techniques: photometric


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