The Astronomical Journal (Jan 2024)

TOI-1994b: A Low-mass Eccentric Brown Dwarf Transiting A Subgiant Star

  • Emma Page,
  • Joshua Pepper,
  • Duncan Wright,
  • Joseph E. Rodriguez,
  • Robert A. Wittenmyer,
  • Stephen R. Kane,
  • Brett Addison,
  • Timothy Bedding,
  • Brendan P. Bowler,
  • Thomas Barclay,
  • Karen A. Collins,
  • Phil Evans,
  • Jonathan Horner,
  • Eric L. N. Jensen,
  • Marshall C. Johnson,
  • John Kielkopf,
  • Ismael Mireles,
  • Peter Plavchan,
  • Samuel N. Quinn,
  • S. Seager,
  • Avi Shporer,
  • Keivan G. Stassun,
  • Stephanie Striegel,
  • Joshua N. Winn,
  • George Zhou,
  • Carl Ziegler

DOI
https://doi.org/10.3847/1538-3881/ad1a18
Journal volume & issue
Vol. 167, no. 3
p. 109

Abstract

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We present the discovery of TOI-1994b, a low-mass brown dwarf transiting a hot subgiant star on a moderately eccentric orbit. TOI-1994 has an effective temperature of ${7700}_{-410}^{+720}$ K, V magnitude of 10.51 mag and log( g ) of ${3.982}_{-0.065}^{+0.067}$ . The brown dwarf has a mass of ${22.1}_{-2.5}^{+2.6}$ M _J , a period of 4.034 days, an eccentricity of ${0.341}_{-0.059}^{+0.054}$ , and a radius of ${1.220}_{-0.071}^{+0.082}$ R _J . TOI-1994b is more eccentric than other transiting brown dwarfs with similar masses and periods. The population of low-mass brown dwarfs may have properties similar to planetary systems if they were formed in the same way, but the short orbital period and high eccentricity of TOI-1994b may contrast this theory. An evolved host provides a valuable opportunity to understand the influence stellar evolution has on the substellar companion’s fundamental properties. With precise age, mass, and radius, the global analysis and characterization of TOI-1994b augments the small number of transiting brown dwarfs and allows the testing of substellar evolution models.

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