An Eccentric Brown Dwarf Eclipsing an M dwarf

Caleb I. Cañas, Suvrath Mahadevan, Chad F. Bender, Noah Isaac Salazar Rivera, Andrew Monson, Corey Beard, Jack Lubin, Paul Robertson, Arvind F. Gupta, William D. Cochran, Connor Fredrick, Fred Hearty, Sinclaire Jones, Shubham Kanodia, Andrea S.J. Lin, Joe P. Ninan, Lawrence W. Ramsey, Christian Schwab, Gu Mundur Stefánsson

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We report the discovery of an M = 67 ± 2M J 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.

Original languageEnglish (US)
Article number89
JournalAstronomical Journal
Issue number2
StatePublished - Feb 1 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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