Unusual Isotopic Abundances in a Fully Convective Stellar Binary
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Crossfield_2019_ApJL_871_L3.pdf
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Author(s)
Lothringer, J. D.
Flores, B.
Mills, E. A. C.
Freedman, R.
Valverde, J.
Miles, B.
Skemer, A.
Crossfield, Ian Jm
Guo, Xueying
Date Issued
January 17, 2019
Journal
The Astrophysical Journal. Letters
Publisher
American Astronomical Society/IOP Publishing
Citation
Crossfield, I. J. M., J. D. Lothringer, B. Flores, E. A. C. Mills, R. Freedman, J. Valverde, B. Miles, X. Guo, and A. Skemer. “Unusual Isotopic Abundances in a Fully Convective Stellar Binary.” The Astrophysical Journal 871, 1 (January 16, 2019): L3. © 2019 The American Astronomical Society
Version
Final published version
Abstract
Low-mass M dwarfs represent the most common outcome of star formation, but their complex emergent spectra hinder detailed studies of their composition and initial formation. The measurement of isotopic ratios is a key tool that has been used to unlock the formation of our solar system, the Sun, and the nuclear processes within more massive stars. We observed GJ 745AB, two M dwarfs orbiting in a wide binary, with the NASA Infrared Telescope Facility/iSHELL spectrograph. Our spectroscopy of CO in these stars at the 4.7 μm fundamental and 2.3 μm first-overtone rovibrational bandheads reveals [superscript 12]C[superscript 16]O, [superscript 13]C[superscript16]O, and [superscript 12]C[superscript18] and in their photospheres. Because the stars are fully convective, the atomic constituents of these isotopologues should be uniformly mixed throughout the stars' interiors. We find that in these M dwarfs, both [superscript 12]C /[superscript 13]C and [superscript 16]O/[superscript 18]O greatly exceed the Solar values. These measurements cannot be explained solely by models of Galactic chemical evolution, but require that the stars formed from an interstellar medium significantly enriched by material ejected from an exploding core-collapse supernova. These isotopic measurements complement the elemental abundances provided by large-scale spectroscopic surveys, and open a new window onto studies of Galactic evolution, stellar populations, and individual systems. Key words: infrared: stars – techniques: spectroscopic – stars: abundances – supernovae: general
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.3847/2041-8213/aaf9b6
