Vincent M. Woolf, Andrew A. West
We present evidence that there is an M dwarf problem similar to the
previously identified G dwarf and K dwarf problems: the number of
low-metallicity M dwarfs is not sufficient to match simple closed-box models of
local Galactic chemical evolution. We estimated the metallicity of 4141 M dwarf
stars with spectra from the Sloan Digital Sky Survey (SDSS) using a molecular
band strength versus metallicity calibration developed using high resolution
spectra of nearby M dwarfs. Using a sample of M dwarfs with measured
magnitudes, parallaxes, and metallicities, we derived a relation that describes
the absolute magnitude variation as a function of metallicity. When we examined
the metallicity distribution of SDSS stars, after correcting for the different
volumes sampled by the magnitude-limited survey, we found that there is an M
dwarf problem, with the number of M dwarfs at [Fe/H] ~ -0.5 less than 1% the
number at [Fe/H] = 0, where a simple model of Galactic chemical evolution
predicts a more gradual drop in star numbers with decreasing metallicity.
View original:
http://arxiv.org/abs/1202.3078
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