AAS 205th Meeting, 9-13 January 2005
Session 77 Properties of Stars
Oral, Tuesday, January 11, 2005, 10:00-11:30am, Royal Palm 4-6

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[77.04] Calibrating estimates of M and K dwarf metallicities using molecular indices from low resolution spectra.

V. M. Woolf, G. Wallerstein (University of Washington)

We report progress in the calibration of a method to determine metallicity of cool dwarf stars (M and K) using molecular indices measured with low resolution spectra. We have used equivalent width analysis with high resolution (\lambda / \Delta \lambda = 33,000) spectra to calculate Fe and Ti abundances for 40 M and K dwarfs with temperatures between 3120 and 4670 K, and \rm -2.44 < [Fe/H] < +0.30. These calculated values will be used to find how molecular indices, e.g. the TiO5 and CaH2 indices, vary with temperature and metallicity. Low mass dwarfs make up the majority of the Galaxy's baryonic mass, so understanding their compositions is important if we are to understand the chemical composition and history of our Galaxy. Because cool dwarfs are intrinsically faint, the number which appear sufficiently bright for high resolution spectra to be measured is small: a method using low resolution spectra is required if we want to find metallicities for a statistically significant number of M and K dwarfs.

We gratefully acknowledge the financial support of the Kennilworth Fund of the New York Community Trust.

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© 2004. The American Astronomical Society.