NOAO >   Observing Info >   Approved Programs >   2012A-0511

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Proposal Information for 2012A-0511


PI: Bo Ma, University of Florida, boma@astro.ufl.edu
Address: Department of Astronomy, 211 Bryant Space Science Center, Gainesville, FL 32611, U.S.A

CoI: Jian Ge, University of Florida
CoI: Ji Wang, University of Florida
CoI: Brian Lee, University of Florida
CoI: Nathan De Lee, University of Florida
CoI: Rui Li, University of Florida
CoI: Scott Fleming, Penn state University

Title: Follow-up of an unbiased binary (brown dwarf) sample using EXPERT

Abstract: The SDSS-III MARVELS survey is a comprehensive radial velocity survey of 3,300 nearby F-K stars, between 7.6 < V < 12.0 in 2008-2012. In the first two years approximately 2000 stars have been monitored for signs of radial velocity variability. One of the defining features of this survey is that the observed stars were drawn from a homogeneous sample. Furthermore, the radial velocity observations are independent of the variability of the observed object, thus creating a sample with a minimal bias in the time-domain. This makes it uniquely suited to constrain theoretical models regarding the formation of companions and looking at the overall distribution of radial velocity variable objects (Armitage 2007). A survey of this size allows for a detailed analysis of the distribution of close binaries (with P<100 days) down to the brown dwarf range (M>80M_Jup). We have studied carefully the MARVELS close binary distribution with period less than 180 days and found a peak around mass ration of 1 (the `twins') in the mass ratio distribution for binaries with period less than 40 days but not for binaries with periods between 40 days and 180 days. Here we propose to extend our study of a sample of binaries with periods less than 180 days to a larger sample with periods less than 2 years. We have selected ~60 binaries with periods greater than 180 days which do not have a complete orbital coverage by the MARVELS observations. We propose to continue monitoring this sample with EXPERT to pin down their precise orbital parameters. We also proposal to follow-up 5 brown dwarf candidates from the new MARVELS processed year 3 data.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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