Planet Hunters Tess I

TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit

N. L. Eisner*, O. Barragán, S. Aigrain, C. Lintott, G. Miller, N. Zicher, T. S. Boyajian, C. Briceño, E. M. Bryant, J. L. Christiansen, A. D. Feinstein, L. M. Flor-Torres, M. Fridlund, D. Gandolfi, J. Gilbert, N. Guerrero, J. M. Jenkins, K. Jones, M. H. Kristiansen, A. Vanderburg & 30 others N. Law, A. R. López-Sánchez, A. W. Mann, E. J. Safron, M. E. Schwamb, K. G. Stassun, H. P. Osborn, J. Wang, A. Zic, C. Ziegler, F. Barnet, S. J. Bean, D. M. Bundy, Z. Chetnik, J. L. Dawson, J. Garstone, A. G. Stenner, M. Huten, S. Larish, L. D. Melanson, T. Mitchell, C. Moore, K. Peltsch, D. J. Rogers, C. Schuster, D. S. Smith, D. J. Simister, C. Tanner, I. Terentev, A. Tsymbal

*Corresponding author for this work

Research output: Contribution to journalArticle

10 Citations (Scopus)
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Abstract

We report on the discovery and validation of TOI 813 b (TIC55525572b), 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* = 1.94 R, M = 1.32 M). 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 MJup (99 per cent 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+0.0027-0.0031 d, a planet radius of 6.71 ± 0.38 R and a semimajor axis of 0.423+0031-0.037 AU. The planet's orbital period combined with the evolved nature of the host star places this object in a relatively underexplored region of parameter space. We estimate that TOI 813 b induces a reflex motion in its host star with a semi-amplitude of ∼6 m s−1, making this a promising system to measure the mass of a relatively long-period transiting planet.

Original languageEnglish
Pages (from-to)750-763
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume494
Issue number1
DOIs
Publication statusPublished - 1 May 2020

Bibliographical note

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, Volume 494, Issue 1, May 2020, Pages 750–763, https://doi.org/10.1093/mnras/staa138. Copyright 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Keywords

  • methods: statistical
  • planets and satellites: detection
  • stars: fundamental parameters
  • stars: individual (TIC-55525572 - TOI 813)

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