Monday, July 15, 2013

1307.3308 (Peng Jiang et al.)

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    [PDF]

Peng Jiang, Jian Ge, Phillip Cargile, Justin R. Crepp, Nathan De Lee, Gustavo F. Porto de Mello, Massimiliano Esposito, Letícia D. Ferreira, Bruno Femenia, Scott W. Fleming, B. Scott Gaudi, Luan Ghezzi, Jonay I. González Hernández, Leslie Hebb, Brian L. Lee, Bo Ma, Keivan G. Stassun, Ji Wang, John P. Wisniewski, Eric Agol, Dmitry Bizyaev, Howard Brewington, Liang Chang, Luiz Nicolaci da Costa, Jason D. Eastman, Garrett Ebelke, Bruce Gary, Stephen R. Kane, Rui Li, Jian Liu, Suvrath Mahadevan, Marcio A. G. Maia, Viktor Malanushenko, Elena Malanushenko, Demitri Muna, Duy Cuong Nguyen, Ricardo L. C. Ogando, Audrey Oravetz, Daniel Oravetz, Kaike Pan, Joshua Pepper, Martin Paegert, Carlos Allende Prieto, Rafael Rebolo, Basilio X. Santiago, Donald P. Schneider, Alaina C. Shelden Bradley, Thirupathi Sivarani, Stephanie Snedden, J. C. van Eyken, Xiaoke Wan, Benjamin A. Weaver, Bo Zhao
We report the discovery of a candidate brown dwarf or a very low mass stellar companion (MARVELS-5b) to the star HIP 67526 from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The radial velocity curve for this object contains 31 epochs spread over 2.5 years. 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 $0.4375 \pm 0.0040$ 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 $T_{\rm{eff}}=6004 \pm 34$ K, a surface gravity $\log g$ [cgs] $=4.55 \pm 0.17$ and a metallicity [Fe/H] $=+0.04 \pm 0.06$. The stellar mass and radius determined through the empirical relationship of Torres et al. (2010), yields 1.10$\pm$0.09 $M_{\sun}$ and 0.92$\pm$0.19 $R_{\sun}$. The minimum mass of MARVELS-5b is $65.0 \pm 2.9 M_{Jup}$, indicating that it is likely to be either a brown dwarf 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$\pm$10 pc from the astrometric measurements of Hipparcos. No stellar tertiary is detected in the high-contrast images taken by either FastCam lucky imaging or Keck adaptive optics imaging, ruling out any star with mass greater than 0.2$M_{\sun}$ at a separation larger than 40 AU.
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