Planet Hunters Tess I: TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit
Reviewartikel, 2020

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.

Stars: fundamental parameters

Methods: statistical

Planets and satellites: detection

Stars: individual (TIC-55525572 - TOI 813)


N. L. Eisner

University of Oxford

O. Barragán

University of Oxford

S. Aigrain

University of Oxford

C. Lintott

University of Oxford

G. Miller

University of Oxford

N. Zicher

University of Oxford

T. S. Boyajian

Louisiana State University

C. Briceño

Cerro Tololo Inter American Observatory

E. Bryant

The University of Warwick

J. L. Christiansen

NASA Ames Research Center

A. D. Feinstein

University of Chicago

L. M. Flor-Torres

Universidad de Guanajuato

Malcolm Fridlund

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik

Universiteit Leiden

D. Gandolfi

Universita degli Studi di Torino

J. Gilbert

Australian National University

N. Guerrero

Massachusetts Institute of Technology (MIT)

Jon M. Jenkins

NASA Ames Research Center

K. Jones

University of Oxford

M. H. Kristiansen

Danmarks Tekniske Universitet (DTU)

A. Vanderburg

The University of Texas at Austin

N. Law

The University of North Carolina at Chapel Hill

A. R. López-Sánchez

Macquarie University

Australian Astronomical Optics

A. Mann

The University of North Carolina at Chapel Hill

E. J. Safron

Louisiana State University

M. E. Schwamb

Gemini Observatory North

Queen's University Belfast

Keivan G. Stassun

Vanderbilt University

Fisk University

H. P. Osborn

Laboratoire d'Astrophysique de Marseille

J. Wang

Yale University

A. Zic

Commonwealth Scientific and Industrial Research Organisation (CSIRO)

The University of Sydney

C. Ziegler

University of Toronto

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


Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 494 1 750-763


Subatomär fysik

Astronomi, astrofysik och kosmologi




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