TOI-1338: TESS' First Transiting Circumbinary Planet

Maxted

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