1. Planet Hunters TESS I: TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit
- Author
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T. Mitchell, Keivan G. Stassun, Z. Chetnik, C. Schuster, J. L. Christiansen, David S. Smith, Megan E. Schwamb, Frank Barnet, J. Garstone, Tabetha S. Boyajian, Ivan Terentev, Cesar Briceno, Nora L. Eisner, Angel R. Lopez-Sanchez, S. Larish, Andrew Vanderburg, Chris Lintott, C. Moore, Hugh P. Osborn, S. J. Bean, Jon M. Jenkins, Martti H. Kristiansen, L. D. Melanson, J. L. Dawson, N. Zicher, Suzanne Aigrain, Emily J. Safron, K. Peltsch, D. M. Bundy, Natalia Guerrero, L. M. Flor-Torres, Dean Joseph Simister, Oscar Barragán, James Gilbert, A. Tsymbal, Ji Wang, K. Jones, D. J. Rogers, Grant Miller, Davide Gandolfi, Marc Huten, Christopher Tanner, A. G. Stenner, Edward M. Bryant, C. Ziegler, Andrew W. Mann, Andrew Zic, Nicholas M. Law, Adina D. Feinstein, Malcolm Fridlund, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
statistical [Methods] ,planets and satellites: detection ,010504 meteorology & atmospheric sciences ,TOI 813) ,stars: individual (TIC-55525572 ,FOS: Physical sciences ,fundamental parameters [Stars] ,01 natural sciences ,Planet ,Saturn ,0103 physical sciences ,individual (TIC-55525572 [stars] ,Transit (astronomy) ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,methods: statistical ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,Subgiant ,Astronomy ,Astronomy and Astrophysics ,Orbital period ,Light curve ,Exoplanet ,detection [Planets and satellites] ,Orbit ,Stars: individual (TIC-55525572 - TOI 813) ,[SDU]Sciences of the Universe [physics] ,13. Climate action ,Space and Planetary Science ,Methods: statistical ,Planets and satellites: detection ,Stars: fundamental parameters ,stars: fundamental parameters ,individual (TIC-55525572, TOI 813) [Stars] ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We report on the discovery and validation of TOI 813b (TIC 55525572 b), a transiting exoplanet identified by citizen scientists in data from NASA's Transiting Exoplanet Survey Satellite (TESS) and the first planet discovered by the Planet Hunters TESS project. The host star is a bright (V = 10.3 mag) subgiant ($R_\star=1.94\,R_\odot$, $M_\star=1.32\,M_\odot$). It was observed almost continuously by TESS during its first year of operations, during which time four individual transit events were detected. The candidate passed all the standard light curve-based vetting checks, and ground-based follow-up spectroscopy and speckle imaging enabled us to place an upper limit of $2 M_{Jup}$ (99 % confidence) on the mass of the companion, and to statistically validate its planetary nature. Detailed modelling of the transits yields a period of $83.8911_{ - 0.0031 } ^ { + 0.0027 }$ days, a planet radius of $6.71 \pm 0.38$ $R_{\oplus}$, and a semi major axis of $0.423_{ - 0.037 } ^ { + 0.031 }$ AU. The planet's orbital period combined with the evolved nature of the host star places this object in a relatively under-explored region of parameter space. We estimate that TOI-813b induces a reflex motion in its host star with a semi-amplitude of $\sim6$ ms$^{-1}$, making this system a promising target to measure the mass of a relatively long-period transiting planet., Accepted for publication in MNRAS (16 pages, 10 figures, 3 tables)
- Published
- 2020