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

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.

MNRAS, accepted

References in corpus (13)

• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• Revised metallicity classes for low-mass stars: dwarfs (dM), subdwarfs (sdM), extreme subdwarfs (esdM), and ultra subdwarfs (usdM)
• Metallicity of M dwarfs IV. A high-precision [Fe/H] and Teff technique from high-resolution optical spectra for M dwarfs
• Carbon and Oxygen in Nearby Stars: Keys to Protoplanetary Disk Chemistry
• The Exemplar T8 Subdwarf Companion of Wolf 1130
• Cool Subdwarf Investigations (CSI) I: New Thoughts for the Spectral Types of K and M Subdwarfs
• The carbon-to-oxygen ratio in stars with planets
• Carbon and Oxygen Abundances in Cool Metal-rich Exoplanet Hosts: A Case Study of the C/O Ratio of 55 Cancri
• A New Sample of Cool Subdwarfs from SDSS: Properties and Kinematics
• Near Infrared Spectroscopy of M Dwarfs. I. CO Molecule as an Abundance Indicator of Carbon

Cited by in corpus (4)

• The SPHINX M-dwarf Spectral Grid. I. Benchmarking New Model Atmospheres to Derive Fundamental M-Dwarf Properties
• The physical mechanism behind M dwarf metallicity indicators and the role of C and O abundances
• Wolf 1130: A Nearby Triple System Containing a Cool, Ultramassive White Dwarf
• Carbon-to-Oxygen Ratios in M dwarfs and Solar-type stars