dc.contributor.author |
Hema, B. P |
|
dc.contributor.author |
Pandey, G |
|
dc.contributor.author |
Kurucz, R. L |
|
dc.contributor.author |
Prieto, C. A |
|
dc.date.accessioned |
2021-02-07T06:11:13Z |
|
dc.date.available |
2021-02-07T06:11:13Z |
|
dc.date.issued |
2020-07-01 |
|
dc.identifier.citation |
The Astrophysical Journal, Vol. 897, No. 1, 32 |
en_US |
dc.identifier.issn |
0004-637X |
|
dc.identifier.uri |
http://hdl.handle.net/2248/7606 |
|
dc.description |
Restricted Access |
en_US |
dc.description.abstract |
The helium-enriched (He-enriched) metal-rich red giants of ω Centauri, discovered by Hema & Pandey using the low-resolution spectra from the Vainu Bappu Telescope, and confirmed by the analyses of the high-resolution spectra obtained from the HRS-South African Large Telescope for LEID 34225 and LEID 39048, are reanalyzed here to determine their degree of He enhancement/hydrogen deficiency (H deficiency). The observed MgH band combined with model atmospheres with differing He/H ratios are used for the analyses. The He/H ratios of these two giants are determined by enforcing the fact that the derived Mg abundances from the Mg i lines and from the subordinate lines of the MgH band must be same for the adopted model atmosphere. The estimated He/H ratios for LEID 34225 and LEID 39048 are 0.15 ± 0.04 and 0.20 ± 0.04, respectively, whereas the normal He/H ratio is 0.10. Following the same criteria for the analyses of the other two comparison stars (LEID 61067 and LEID 32169), a normal He/H ratio of 0.10 is obtained. The He/H ratio of 0.15–0.20 corresponds to a mass fraction of helium (Z(He) = Y) of about 0.375–0.445. The range of helium enhancement and the derived metallicity of the program stars are in line with those determined for ω Cen's blue main-sequence stars. Hence, our study provides the missing link for the evolutionary track of the metal-rich helium-enhanced population of ω Centuari. This research work is the very first spectroscopic determination of the amount of He enhancement in the metal-rich red giants of ω Centauri using the Mg i and MgH lines. |
en_US |
dc.language.iso |
en |
en_US |
dc.publisher |
IOP Publishing |
en_US |
dc.relation.uri |
https://doi.org/10.3847/1538-4357/ab93bd |
|
dc.rights |
© The American Astronomical Society |
|
dc.subject |
Globular star clusters |
en_US |
dc.subject |
Chemical abundances |
en_US |
dc.subject |
Red giant stars |
en_US |
dc.subject |
Hydrogen deficient stars |
en_US |
dc.subject |
Chemically peculiar stars |
en_US |
dc.subject |
Stellar evolutionary tracks |
en_US |
dc.title |
Helium Enhancement in the Metal-rich Red Giants of ω Centauri |
en_US |
dc.type |
Article |
en_US |