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arXiv · 2401.09121

Measuring Hydrogen-to-Helium Ratio in Cool Stars

B. P. Hema·Gajendra Pandey
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Abstract

Conventionally, the helium-to-hydrogen ratio for the stars are adopted to be 0.1, as standard, unless, the stars are severely deficient in hydrogen like in RCB-class, or the stars' helium abundance is accurately measured using He I transitions in warm/hotter stars. In our study, the small change in helium-to-hydrogen ratio (from standard value, 0.1) in normal giants were detected from the large difference (> 0.3 dex) in the Mg-abundance measured from Mg I lines and the subordinate lines of (0,0) MgH band. These are the stars that are mildly hydrogen-deficient/He-enhanced. Such stars were spectroscopically discovered for the first time among giants of the globular cluster Omega Centauri. The sample selection, observations, methodology and results are discussed in detail.

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B. P. Hema, Gajendra Pandey. 2024-01-17. Measuring Hydrogen-to-Helium Ratio in Cool Stars. https://arxiv.org/abs/2401.09121

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