Very Low-Mass Stellar and Substellar Companions to Solar-Like Stars From Marvels. VI. A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646

Bo Ma, University of Florida
Jian Ge, University of Florida
Alex Wolszczan, Pennsylvania State University
Matthew W. Muterspaugh, Tennessee State University
Brian Lee, University of Florida
Gregory W. Henry, Tennessee State University
Donald P. Schneider, Pennsylvania State University
Eduardo L. Martín, Centro de Astrobiología
Andrzej Niedzielski, Nicolaus Copernicus University in Toruń
Jiwei Xie, University of Florida
Scott W. Fleming, Space Telescope Science Institute
Neil Thomas, University of Florida
Michael H. Williamson, Tennessee State University
Zhaohuan Zhu, Princeton University
Eric Agol, University of Washington
Dmitry Bizyaev, Apache Point Observatory and New Mexico State University
Luiz Nicolaci da Costa, Laboratŕio Interinstitucional de e-Astronomia
Peng Jiang, University of Florida
Aldo Fabricio Martinez Fiorenzano, Fundación Galileo Galilei-INAF
Jonay I. González Hernández, Instituto de Astrofísica de Canaria
Pengcheng Guo, University of Florida
Nolan Grieves, University of Florida
Rui Li, University of Florida
Jane Liu, University of Florida
Suvrath Mahadevan, Pennsylvania State University
Tsevi Mazeh, Tel Aviv University
Duy Cuong Nguyen, University of Toronto
Martin Paegert, Vanderbilt University
Sirinrat Sithajan, University of Florida
Keivan Stassun, Vanderbilt University
Sivarani Thirupathi, University of Florida
Julian C. van Eyken, University of California, Santa Barbara
Xiaoke Wan, University of Florida
Ji Wang, Yale University
John P. Wisniewski, University of Oklahoma
Bo Zhao, University of Florida
Shay Zucker, Tel Aviv University


We report the detections of a giant planet (MARVELS-7b) and a brown dwarf (BD) candidate (MARVELS-7c) around the primary star in the close binary system, HD 87646. To the best of our knowledge, it is the first close binary system with more than one substellar circumprimary companion that has been discovered. The detection of this giant planet was accomplished using the first multi-object Doppler instrument (KeckET) at the Sloan Digital Sky Survey (SDSS) telescope. Subsequent radial velocity observations using the Exoplanet Tracker at the Kitt Peak National Observatory, the High Resolution Spectrograph at the Hobby Eberley telescope, the "Classic" spectrograph at the Automatic Spectroscopic Telescope at the Fairborn Observatory, and MARVELS from SDSS-III confirmed this giant planet discovery and revealed the existence of a long-period BD in this binary. HD 87646 is a close binary with a separation of ∼22 au between the two stars, estimated using the Hipparcos catalog and our newly acquired AO image from PALAO on the 200 inch Hale Telescope at Palomar. The primary star in the binary, HD 87646A, has ${T}_{\mathrm{eff}}$ = 5770 ± 80 K, log g = 4.1 ± 0.1, and [Fe/H] = −0.17 ± 0.08. The derived minimum masses of the two substellar companions of HD 87646A are 12.4 ± 0.7 ${M}_{\mathrm{Jup}}$ and 57.0 ± 3.7 ${M}_{\mathrm{Jup}}$. The periods are 13.481 ± 0.001 days and 674 ± 4 days and the measured eccentricities are 0.05 ± 0.02 and 0.50 ± 0.02 respectively. Our dynamical simulations show that the system is stable if the binary orbit has a large semimajor axis and a low eccentricity, which can be verified with future astrometry observations.