We report the discovery of a M=67±2MJ brown dwarf transiting the early M dwarf TOI-2119 on an eccentric orbit (e=0.3362±0.0005) at an orbital period of 7.200861±0.000005 days. We confirm the brown dwarf nature of the transiting companion using a combination of ground-based and space-based photometry and high-precision velocimetry from the Habitable-zone Planet Finder. Detection of the secondary eclipse with TESS photometry enables a precise determination of the eccentricity and reveals the brown dwarf has a brightness temperature of 2100±80 K, a value which is consistent with an early L dwarf. TOI-2119 is one of the most eccentric known brown dwarfs with P<10 days, possibly due to the long circularization timescales for an object orbiting an M dwarf. We assess the prospects for determining the obliquity of the host star to probe formation scenarios and the possibility of additional companions in the system using Gaia EDR3 and our radial velocities.
@article{arxiv.2112.03959,
title = {An eccentric Brown Dwarf eclipsing an M dwarf},
author = {Caleb I. Cañas and Suvrath Mahadevan and Chad F. Bender and Noah Isaac Salazar Rivera and Andrew Monson and Corey Beard and Jack Lubin and Paul Robertson and Arvind F. Gupta and William D. Cochran and Connor Fredrick and Fred Hearty and Sinclaire Jones and Shubham Kanodia and Andrea S. J. Lin and Joe P. Ninan and Lawrence W. Ramsey and Christian Schwab and Guðmundur Stefánsson},
journal= {arXiv preprint arXiv:2112.03959},
year = {2022}
}
Comments
31 pages, 8 figures, 3 tables, published in AJ, minor revisions to match published version