Near Infrared Spectroscopy of M Dwarfs. II. H2O Molecule as an Abundance Indicator of Oxygen
arXiv:1412.6873 · doi:10.1093/pasj/psu160
Abstract
Based on the near infrared spectra (R~20000) of M dwarfs, oxygen abundances are determined from the ro-vibrational lines of H2O. Although H2O lines in M dwarfs are badly blended each other and the continuum levels are depressed appreciably by the collective effect of numerous H2O lines themselves, quantitative analysis of H2O lines has been carried out by referring to the pseudo-continua both on the observed and theoretical spectra. For this purpose, the pseudo-continuum on the theoretical spectrum has been evaluated by the use of the recent high-precision H2O line-list. Then, we propose a simple and flexible method of analyzing equivalent widths (EWs) of blended features by the use of a mini curve-of-growth (CG), which is a small portion of the usual CG around the observed EW. The mini CG is generated by using the theoretical EWs evaluated from the synthetic spectrum by exactly the same way as the EWs are measured from the observed spectrum. The observed EW is converted to the abundance by the use of the mini CG, and the process is repeated for all the observed EWs line-by-line or blend-by-blend. In cool M dwarfs, almost all the oxygen atoms left after CO formation are in stable H2O molecules, which suffer little change for the uncertainties due to imperfect modelling of the photospheres. Then the numerous H2O lines are excellent abundance indicators of oxygen. The oxygen abundances are determined to be logAo between -3.5 and -3.0 in 38 M dwarfs. The resulting O/C ratios plotted against logAc appear to be systematically smaller in the carbon-rich M dwarfs, showing the different formation histories of oxygen and carbon in the chemical evolution of the Galactic disk. Also, O/Fe ratios in most M dwarfs are closer to the solar O/Fe ratio based on the classical high oxygen abundance rather than on the recently downward revised low value.
arXiv comment35 pages, 18 figures, 9 tables + 2 tables for electronic version only, Corrected typos, accepted by PASJ
References in corpus (23)
- The chemical composition of the Sun
- The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
- Validation of the new Hipparcos reduction
- A high accuracy computed water line list
- Stellar Diameters and Temperatures II. Main Sequence K & M Stars
- A Reappraisal of the Solar Photospheric C/O Ratio
- On the Metal-Richness of M Dwarfs with Planets
- Dust in the Photospheric Environment: Unified Cloudy Models of M, L, and T Dwarfs
- Stellar Diameters and Temperatures V. Eleven Newly Characterized Exoplanet Host Stars
- Metallicity of M dwarfs III. Planet-metallicity and planet-stellar mass correlations of the HARPS GTO M dwarf sample
- Imaging the dynamical atmosphere of the red supergiant Betelgeuse in the CO first overtone lines with VLTI/AMBER
- Accurate M Dwarf Metallicities from Spectral Synthesis: A Critical Test of Model Atmospheres
- M-dwarf metallicities - A high-resolution spectroscopic study in the near infrared
- Dust in the Photospheric Environment III. A Fundamental Element in the Characterization of Ultracool Dwarfs
- ISO-SWS calibration and the accurate modelling of cool-star atmospheres - IV. G9 to M2 stars
- Cool luminous stars: the hybrid nature of their infrared spectra -- Carbon, oxygen, and their isotopic abundances in 23 K - M giant stars
- Water in K and M giant stars unveiled by ISO
- Properties of the CO and HO MOLsphere of the red supergiant Betelgeuse from VLTI/AMBER observations
- Comparative Modelling of the Spectra of Cool Giants
- Detection of Water Vapor in the Photosphere of Arcturus
- Warm water vapor envelope in the supergiants alf Ori and alf Her and its effects on the apparent size from the near-infrared to the mid-infrared
- Near Infrared Spectroscopy of M Dwarfs. I. CO Molecule as an Abundance Indicator of Carbon
- Possible Evidence for Metal Accretion onto the Surfaces of Metal-Poor Main-Sequence Stars
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- Carbon-to-Oxygen Ratios in M dwarfs and Solar-type stars
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