Very-low-mass stellar and substellar companions to solar-like stars from marvels. III. A short-period brown dwarf candidate around an active g0iv subgiant

Bo Ma, Jian Ge, Rory Barnes, Justin R. Crepp, Nathan De Lee, Leticia Dutra-Ferreira, Massimiliano Esposito, Bruno Femenia, Scott W. Fleming, B. Scott Gaudi, Luan Ghezzi, Leslie Hebb, Jonay I. Gonzalez Hernandez, Brian L. Lee, G. F.Porto De Mello, Keivan G. Stassun, Ji Wang, Johnp Wisniewski, Eric Agol, Dmitry BizyaevPhillip Cargile, Liang Chang, Luiz Nicolaci Da Costa, Jasond Eastman, Bruce Gary, Peng Jiang, Stephen R. Kane, Rui Li, Jian Liu, Suvrath Mahadevan, Marcioa G. Maia, Demitri Muna, Duy Cuong Nguyen, Ricardo L.C. Ogando, Daniel Oravetz, Joshua Pepper, Martin Paegert, Carlos Allende Prieto, Rafael Rebolo, Basilio X. Santiago, Donaldp Schneider, Alaina Shelden, Audrey Simmons, Thirupathi Sivarani, J. C. Van Eyken, Xiaoke Wan, Benjamin A. Weaver, Bo Zhao

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


We present an eccentric, short-period brown dwarf candidate orbiting the active, slightly evolved subgiant star TYC2087-00255-1, which has effective temperature T eff = 5903 ± 42K, surface gravity log (g) = 4.07 ± 0.16(cgs), and metallicity [Fe/H] = -0.23 ± 0.07. This candidate was discovered using data from the first two years of the Multi-object APO Radial Velocity Exoplanets Large-area Survey, which is part of the third phase of Sloan Digital Sky Survey. From our 38 radial velocity measurements spread over a two-year time baseline, we derive a Keplerian orbital fit with semi-amplitude K = 3.571 ± 0.041kms-1, period P = 9.0090 ± 0.0004days, and eccentricity e = 0.226 ± 0.011. Adopting a mass of 1.16 ± 0.11 M· for the subgiant host star, we infer that the companion has a minimum mass of 40.0 ± 2.5 M ·Jup. Assuming an edge-on orbit, the semimajor axis is 0.090 ± 0.003AU. The host star is photometrically variable at the sim;1% level with a period of sim;13.16 ± 0.01 days, indicating that the host star spin and companion orbit are not synchronized. Through adaptive optics imaging we also found a point source 643 ± 10 mas away from TYC2087-00255-1, which would have a mass of 0.13 M· if it is physically associated with TYC2087-00255-1 and has the same age. Future proper motion observation should be able to resolve if this tertiary object is physically associated with TYC2087-00255-1 and make TYC2087-00255-1 a triple body system. Core Ca II H and K line emission indicate that the host is chromospherically active, at a level that is consistent with the inferred spin period and measured v rotsin i, but unusual for a subgiant of this T eff. This activity could be explained by ongoing tidal spin-up of the host star by the companion.

Original languageEnglish (US)
Article number20
JournalAstronomical Journal
Issue number1
StatePublished - Jan 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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