NOAO >   Observing Info >   Approved Programs >   2007B-0189

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Proposal Information for 2007B-0189


PI: Brian D. Mason, US Naval Observatory, bdm@usno.navy.mil
Address: Astrometry, 3450 Massachusetts Avenue NW, Washington, DC 20392-5420, USA

CoI: William I. Hartkopf, US Naval Observatory
CoI: Deepak Raghavan, Georgia State University / CHARA

Title: Nearby Dwarf Stars: Duplicity, Binarity, and Masses

Abstract: Double stars have proven to be both a blessing and a curse for astronomers since their discovery over two centuries ago. They remain the only reliable source of masses, the most fundamental parameter defining stars. On the other hand, their sobriquet ``vermin of the sky'' is well-earned, due to the complications they present to both observers and theoreticians. These range from non-linear proper motions to stray light in detectors, to confusion in pointing of instruments due to non-symmetric point spread functions, to angular momentum conservation in multiple stars which results in binaries closer than allowed by evolution of two single stars. This proposal is an effort to address both their positive and negative aspects, through speckle interferometric observations, targeting ~1200 systems where useful information can be obtained with only a single additional observation. The proposed work will refine current statistics regarding duplicity (chance alignments of nearby point sources) and binarity (actual physical relationships), and improve the precisions and accuracies of stellar masses. Several targets support Raghavan's Ph.D. thesis, which is a comprehensive survey aimed at determining the multiplicity fraction among solar-type stars.


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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