Discovery of relatively hydrogen-poor giants in the Galactic globular cluster Omega Centauri
arXiv:1408.1205 · doi:10.1088/2041-8205/792/2/L28
Abstract
In this letter, the results of our low-resolution spectroscopic survey for identifying the hydrogen-deficient (H-deficient) stars in the red giant sample of the globular cluster Omega Cen are reported. Spectral analyses were carried out on the basis of the strengths of (0,0) MgH band and the Mg b triplet. In our sample, four giants were identified with weak/absent MgH bands in their observed spectra not as expected for their well determined stellar parameters. The Mg abundances for the program stars were determined from subordinate lines of the MgH band to the blue of the Mg b triplet, using the spectral synthesis technique. The derived Mg abundances for the program stars were as expected for the red giants of Omega Cen (Norris & Da Costa 1995), except for the four identified candidates. Determined Mg abundances of these four candidates are much lower than that expected for the red giants of Omega Cen, and are unacceptable based on the strengths of Mg b triplet in their observed spectra. Hence, the plausible reason for the weak/absent MgH bands in the observed spectra of these stars is a relatively lower abundance of hydrogen in their atmospheres. These giants may belong to the group of helium enriched red giants of Omega Cen.
arXiv comment13 pages, 3 figures, Accepted for publication in ApJ Letters
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Cited by in corpus (5)
- Helium Enhancement in the Metal Rich Red Giants of Omega Centauri
- High resolution spectroscopy of the relatively hydrogen-poor metal rich giants in the globular cluster Omega Centauri
- Omega Centauri: weak MgH-band in red giants directly trace the helium content
- Helium Abundance of the Sun: A Spectroscopic Analysis
- Investigation of the Helium Enhancement in a Super Lithium Rich Giant HD 77361