TOI-1338: TESS' First Transiting Circumbinary Planet

Maxted

doi:10.3847/1538-3881/ab8a48

TOI-1338: TESS' First Transiting Circumbinary Planet

Maxted

Authors

Pierre Maxted p.maxted@keele.ac.uk

Abstract

We report the detection of the first circumbinary planet (CBP) found by Transiting Exoplanet Survey Satellite (TESS). The target, a known eclipsing binary, was observed in sectors 1 through 12 at 30 minute cadence and in sectors 4 through 12 at 2 minute cadence. It consists of two stars with masses of 1.1 M ? and 0.3 M ? on a slightly eccentric (0.16), 14.6 day orbit, producing prominent primary eclipses and shallow secondary eclipses. The planet has a radius of ~6.9 R ? and was observed to make three transits across the primary star of roughly equal depths (~0.2%) but different durations—a common signature of transiting CBPs. Its orbit is nearly circular (e ˜ 0.09) with an orbital period of 95.2 days. The orbital planes of the binary and the planet are aligned to within ~1°. To obtain a complete solution for the system, we combined the TESS photometry with existing ground-based radial-velocity observations in a numerical photometric-dynamical model. The system demonstrates the discovery potential of TESS for CBPs and provides further understanding of the formation and evolution of planets orbiting close binary stars.

Acceptance Date	Apr 15, 2020
Publication Date	May 7, 2020
Journal	Astronomical Journal
Print ISSN	0004-6256
Publisher	American Astronomical Society
DOI	https://doi.org/10.3847/1538-3881/ab8a48
Keywords	exoplanet astronomy, eclipsing binary stars
Publisher URL	https://iopscience.iop.org/article/10.3847/1538-3881/ab8a48