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arXiv · 1510.06985

M dwarfs and the fraction of high carbon-to-oxygen stars in the solar neighbourhood

John E. Gizis·Zachary Marks·Peter H. Hauschildt
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Abstract

We investigate the frequency of high carbon-to-oxygen (C/O $= 0.9$) M dwarf stars in the solar neighbourhood. Using synthetic spectra, we find that such M dwarfs would have weaker TiO bands relative to hydride features. Similar weakening has already been detected in M-subdwarf (sdM) stars. By comparing to existing spectroscopic surveys of nearby stars, we show that less than one percent of nearby stars have high carbon-to-oxygen ratios. This limit does not include stars with C/O$=0.9$, [m/H]$>0.3$, and [C/Fe]$>0.1$, which we predict to have low-resolution optical spectra similar to solar metallicity M dwarfs.

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John E. Gizis, Zachary Marks, Peter H. Hauschildt. 2015-10-23. M dwarfs and the fraction of high carbon-to-oxygen stars in the solar neighbourhood. https://doi.org/10.1093/mnras/stv2479

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