TOI-222: a single-transit TESS candidate revealed to be a 34-day eclipsing binary with CORALIE, EulerCam and NGTS
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(-0.10)(+0.39) R-circle dot and a mass of 0.23 +/- 0.01 M-circle dot. 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. ; Swiss National Science Foundation (SNSF) Geneva University Swiss National Science Foundation (SNSF) Science & Technology Facilities Council (STFC) ST/M001962/1 ST/S002642/1 Science & Technology Facilities Council (STFC) ST/L000733/1 ST/P000495/1 ST/N000757/1 ST/P000312/1 1226157 STFC via an Ernest Rutherford Fellowship ST/R00384X/1 MIT's Kavli Institute Austrian Research Promotion Agency (FFG) 859724 Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) PB06 CONICYT-PFCHA, Chile 21191829 Millennium Institute of Astrophysics (MAS) Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) CONICYT FONDECYT 1161218 3180246 1171208 Ministry for the Economy, Development, and Tourism's Programa Iniciativa Científica Milenio IC120009 European Research Council (ERC) 681601 ERC under the European Union 320964 Australian Research Council LE160100001 DP180100972 Mount Cuba Astronomical Foundation University of Texas at Austin UNSW Australia MIT Nanjing University George Mason University University of Louisville University of California System University of Florida NASA's Science Mission directorate University of Southern Queensland