Spectroscopy of extremely metal-poor stars

We present results from the analysis of high-resolution spectra obtained with the Keck HIRES spectrograph for a sample of 17 candidate extremely metal-poor (EMP) stars originally selected from commissioning data obtained with the SkyMapper telescope. Fourteen of the stars have not been observed previously at high dispersion. Three have [Fe/H]=<-3.0, while the remainder, with two more metal-rich exceptions, have -3.0=<[Fe/H]=<-2.0dex. Apart from Fe, we also derive abundances for the elements C, N, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, and Zn, and for n-capture elements Sr, Ba, and Eu. None of the current sample of stars is found to be carbon-rich. In general, our chemical abundances follow previous trends found in the literature, although we note that two of the most metal-poor stars show very low [Ba/Fe] (~-1.7) coupled with low [Sr/Ba] (~-0.3). Such stars are relatively rare in the Galactic halo. One further star, and possibly two others, meet the criteria for classification as a r-I star. This study, together with that of Jacobson et al. (2015ApJ...807..171J, Cat. J/ApJ/807/171), completes the outcomes of the SkyMapper commissioning data survey for EMP stars.

Cone search capability for table J/MNRAS/485/5153/table1 (Details of the target stars and the Keck HIRES observations)

Identifier
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/MNRAS/485/5153
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/485/5153
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/485/5153
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/MNRAS/485/5153
Provenance
Creator Marino A.F.; Da Costa G.S.; Casey A.R.; Asplund M.; Bessell M.S.,Frebel A.; Keller S.C.; Lind K.; Mackey A.D.; Murphy S.J.; Nordlander T.,Norris J.E.; Schmidt B.P.; Yong D.
Publisher CDS
Publication Year 2022
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Interdisciplinary Astronomy; Natural Sciences; Observational Astronomy; Physics; Stellar Astronomy