1. Carbon and Oxygen Isotopic Ratios. II. Semiregular Variable M Giants
- Author
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Oscar Straniero, Thomas Lebzelter, Kenneth H. Hinkle, Kristie A. Nault, Catherine A. Pilachowski, and David L. Lambert
- Subjects
010504 meteorology & atmospheric sciences ,chemistry.chemical_element ,FOS: Physical sciences ,Astrophysics ,01 natural sciences ,Oxygen ,Spectral line ,law.invention ,Stellar nucleosynthesis ,law ,Abundance (ecology) ,0103 physical sciences ,Asymptotic giant branch ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Physics ,Astronomy and Astrophysics ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,chemistry ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Hydrostatic equilibrium ,Carbon - Abstract
Carbon and oxygen isotopic ratios are reported for a sample of 51 SRb- and Lb-type variable asymptotic giant branch stars. Vibration-rotation first- and second-overtone CO lines in 1.5-2.5 mum spectra were measured to derive isotopic ratios for 12C/13C, 16O/17O, and 16O/18O. Comparisons with previous measurements for individual stars and with various samples of evolved stars, as available in the extant literature, are discussed. Using the oxygen isotopic ratios, the masses of the SRb stars can be derived. Combining the masses with Gaia luminosities, the SRb stars are shown to be antecedents of the Mira variables. The limiting parameters where plane-parallel, hydrostatic equilibrium model atmospheres can be used for abundance analysis of M giants are explored.
- Published
- 2019
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