We present spectra of three M subdwarfs which are common proper motion companions to F or G subdwarfs of known metallicity. The assumption that the companions have the same composition allows us to test the Gizis (1997, AJ, 113, 806) M subdwarf classification system and its correspondence to metallicity. The results are in excellent agreement with the Gizis (1997) scale, thereby showing that the Allard & Hauschildt (1995, ApJ, 445, 433) Extended model atmospheres agree well in the 6200 -- 7400 Angstrom region for cool metal-poor stars. We also show that the results are consistent with the main sequences of globular clusters using the Reid (1997, AJ, 114, 161) distance scale.
@article{arxiv.astro-ph/9708244,
title = {M Subdwarf Secondaries: A Test of the Metallicity Scale},
author = {John E. Gizis and I. Neill Reid},
journal= {arXiv preprint arXiv:astro-ph/9708244},
year = {2009}
}
Comments
10 pages, 3 figures, AASTeX, to appear in the November 1997 PASP