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Title: Planet Hunters TESS I: TOI 813, a subgiant hosting a transiting Saturn-sized planet on an 84-day orbit
ABSTRACT 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 ($$R_\star =1.94\, R_\odot$$, $$M_\star =1.32\, M_\odot$$). 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 $$2\, M_{\rm Jup}$$ (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 $$83.8911 _{ - 0.0031 } ^ { + 0.0027 }$$ d, a planet radius of 6.71 ± 0.38 R⊕ and a semimajor 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 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.  more » « less
Award ID(s):
1835530
PAR ID:
10207040
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; « less
Date Published:
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
494
Issue:
1
ISSN:
0035-8711
Page Range / eLocation ID:
750 to 763
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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