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 VanderburgN 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 journalJournal articleResearchpeer-review

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We report on the discovery and validation of TOI 813 b (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⋆ = 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% confidence) on the mass of the companion, and to statistically validate its planetary nature.
Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Pages (from-to)750–763
Publication statusPublished - 2020

Bibliographical note

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2020 The author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.


  • Methods: statistical
  • Planets and satellites: detection
  • Stars: fundamental parameters
  • Stars:individual (TIC-55525572, TOI 813)


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