Very Low Mass Stellar and Substellar Companions to Solar-like Stars from MARVELS. IV. A Candidate Brown Dwarf or Low-mass Stellar Companion to HIP 67526
Bizyaev, Dmitry; Brewington, Howard; Ebelke, Garrett; Ge, Jian; Malanushenko, Elena; Malanushenko, Viktor; Muna, Demitri; Oravetz, Daniel; Pan, Kaike; Schneider, Donald P.; Weaver, Benjamin A.; Mahadevan, Suvrath; Kane, Stephen R.; Pepper, Joshua; Stassun, Keivan G.; Cargile, Phillip; Crepp, Justin R.; Sivarani, Thirupathi; Wisniewski, John P.; Gaudi, B. Scott; Eastman, Jason D.; Esposito, Massimiliano; Fleming, Scott W.; Chang, Liang; Allende Prieto, Carlos; Jiang, Peng; Paegert, Martin; Hebb, Leslie; De Lee, Nathan; Agol, Eric; Wang, Ji; Li, Rui; Rebolo, Rafael; Maia, Marcio A. G.; Ma, Bo; González Hernández, Jonay I.; Ogando, Ricardo L. C.; Santiago, Basilio X.; Snedden, Stephanie; Oravetz, Audrey; Femenia, Bruno; Porto de Mello, Gustavo F.; Nicolaci da Costa, Luiz; Nguyen, Duy Cuong; Wan, Xiaoke; Zhao, Bo; Ferreira, Letícia D.; Ghezzi, Luan; Lee, Brian L.; Gary, Bruce; Liu, Jian; Shelden Bradley, Alaina C.; van Eyken, J. C.
United States, China, Brazil, Spain, India
Abstract
We report the discovery of a candidate brown dwarf (BD) or a very low mass stellar companion (MARVELS-5b) to the star HIP 67526 from the Multi-object Apache point observatory Radial Velocity Exoplanet Large-area Survey (MARVELS). The radial velocity curve for this object contains 31 epochs spread over 2.5 yr. Our Keplerian fit, using a Markov Chain Monte Carlo approach, reveals that the companion has an orbital period of 90.2695^{+0.0188}_{-0.0187} days, an eccentricity of 0.4375 ± 0.0040, and a semi-amplitude of 2948.14^{+16.65}_{-16.55} m s-1. Using additional high-resolution spectroscopy, we find the host star has an effective temperature T eff = 6004 ± 34 K, a surface gravity log g (cgs) =4.55 ± 0.17, and a metallicity [Fe/H] =+0.04 ± 0.06. The stellar mass and radius determined through the empirical relationship of Torres et al. yields 1.10 ± 0.09 M ⊙ and 0.92 ± 0.19 R ⊙. The minimum mass of MARVELS-5b is 65.0 ± 2.9M Jup, indicating that it is likely to be either a BD or a very low mass star, thus occupying a relatively sparsely populated region of the mass function of companions to solar-type stars. The distance to this system is 101 ± 10 pc from the astrometric measurements of Hipparcos. No stellar tertiary is detected in the high-contrast images taken by either FastCam lucky imaging or Keck adaptive optics imaging, ruling out any star with mass greater than 0.2 M ⊙ at a separation larger than 40 AU.