NOAO >   Observing Info >   Approved Programs >   2011B-0581

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Proposal Information for 2011B-0581


PI: Sebastien Lepine, American Museum of Natural History, lepine@amnh.org
Address: Astrophysics, Central Park West at 79th street, New York, NY 10024, USA

CoI: Saurav Dhital, Vanderbilt University
CoI: Andrew A. West, Boston University

Title: Calibration the absolute metallicity scale of M subdwarfs using wide, common proper motion binaries.

Abstract: Metallicity is a fundamental parameter but is very hard to measure in low-mass stars such as M dwarfs and M subdwarfs (sdM) due to the complexity of their emerging spectra. Metallicity sensitive features have recently been identified in the metal-poor M subdwarfs but their calibration is currently based on just a few early-type sdM objects, which are just bright enough for Fe abundance measurements with high- resolution spectroscopy; all other known M subdwarfs are too faint for similar measurement to be carried out. However, we have just identified 60 common proper motion pairs, where the secondary is a faint, M subdwarf but the primary is a much brighter star of subtype F/G/K. Metallicities can be estimated for these primaries using existing stellar parameter pipelines. We propose to use these wide halo binaries to calibrate the metallicity scale of the M subdwarfs by measuring the metallicity of the more massive F/G/K primary.


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