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A new sample of extremely/ultra metal-poor stars

Date

2008

Authors

Garcia Perez, A E
Christlieb, N
Ryan, Sean G
Beers, Timothy C
Aoki, Wako
Asplund, Martin
Barklem, Paul S
Bessell, Michael
Eriksson, Kjell
Frebel, Anna

Journal Title

Journal ISSN

Volume Title

Publisher

IOP Publishing

Abstract

A sample of 30 very metal-poor stars from the Hamburg-European Southern Observatory (ESO) objective-prism survey have been observed at high spectral resolution at the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle Spectrograph (UVES). Two of the observed stars are very interesting not only because of their very low iron content, approximately four orders of magnitude lower than the solar value, but also because we detected the neutral lithium resonance line at 670.8 nm. Hydrogen lines suggest that the two observed stars have effective temperatures around 6000-6250 K and according to isochrones, they are either on the main-sequence or on the subgiant branch, in which case they would probably be the most metal-poor dwarfs or warm subgiants with lithium detections known. These detections would allow to determine more accurately the slope of the trend of the lithium abundance with [Fe/H] than was possible with samples of unevolved stars restricted to higher metallicities.

Description

Keywords

Keywords: Echelle spectrograph; Effective temperature; European Southern Observatory; Four-order; High spectral resolution; Hydrogen lines; Iron content; Isochrones; Metal-poor star; Metallicities; Neutral lithium; Subgiants; Very large telescope; Lithium; Optical

Citation

Source

Physica Scripta, Volume T133

Type

Conference paper

Book Title

Entity type

Access Statement

License Rights

DOI

10.1088/0031-8949/2008/T133/014036

Restricted until

2037-12-31