dc.contributor.author |
Meenakshi, P |
|
dc.contributor.author |
Goswami, A |
|
dc.date.accessioned |
2021-07-23T04:37:33Z |
|
dc.date.available |
2021-07-23T04:37:33Z |
|
dc.date.issued |
2021-05-01 |
|
dc.identifier.citation |
The Astrophysical Journal, Vol. 912, No. 1, 74 |
en_US |
dc.identifier.issn |
1538-4357 |
|
dc.identifier.uri |
http://hdl.handle.net/2248/7803 |
|
dc.description |
Restricted Access |
en_US |
dc.description.abstract |
We present elemental abundance results for HE 2148−2039 and HE 2155−2043 based on a detailed high-resolution spectroscopic analysis. The high-resolution Subaru/High Dispersion Spectrograph (HDS) spectra used for our analysis have a resolution of R ~ 60,000. Although limited information based on photometry and low-resolution spectroscopy is available, we present for the first time an abundance analysis based on high-resolution spectra for both objects. Our analysis shows that the two objects are extremely metal-poor with [Fe/H] < −3. Among the neutron-capture elements, abundances of only Sr and Ba could be determined in our program stars. For both the objects [Ba/Fe] is found to be <0. While strontium is underabundant in HE 2148−2039 with [Sr/Fe] ~ −2.02, Sr is near solar in HE 2155−2043. The locations of the program stars in the absolute carbon abundance, A(C) versus [Fe/H] diagram, show that HE 2148−2039 is a carbon-enhanced metal-poor (CEMP)-no Group II object and HE 2155−2043 is a CEMP-no Group III object. Observed [Sr/Ba] ratios are characteristics of a fast rotating massive star progenitor for HE 2155−2043 and a metal-poor asymptotic giant branch (AGB) star for HE 2148−2039. The estimated [Sc/Mn] as well as [C/Cr] ratios in HE 2155−2043 show that the surface chemical composition of this object is mono-enriched. The surface chemical composition of HE 2148−2039 is also found to be mono-enriched based on the [Mg/C] ratio. With respect to their locations in the [C/N] versus Teff diagram, HE 2148−2039 shows signatures of mixing, and HE 2155−2043 falls in the unmixed region of the [C/N] versus Teff plot. Kinematic analysis shows that both objects belong to the Galactic halo population. |
en_US |
dc.language.iso |
en |
en_US |
dc.publisher |
IOP Publishing |
en_US |
dc.relation.uri |
https://doi.org/10.3847/1538-4357/abec45 |
|
dc.rights |
© The American Astronomical Society |
|
dc.subject |
Population II stars |
en_US |
dc.title |
Chemical Analysis of Two Extremely Metal-poor Stars HE 2148-2039 and HE 2155-2043 |
en_US |
dc.type |
Article |
en_US |