Chemical abundance analysis of the extremely metal-poor star HE 1300+0157
2007 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 658, no 1, 534-552 p.Article in journal (Refereed) Published
We present a detailed chemical abundance analysis of HE 1300+0157, a subgiant with Fe/H = -3.9. Froma high-resolution, high-S/N Subaru HDS spectrum we find the star to be enriched in C ([C/Fe](1D) similar to +1.4) and O ([O/Fe](1D) similar to +1.8). With the exception of these species, HE 1300+0157 exhibits an elemental abundance pattern similar to that found in many other very and extremely metal-poor stars. The Li abundance is lower than the Spite plateau value, in agreement with expectation for its evolutionary status. Of particular interest, no neutron-capture elements are detected in HE 1300+0157. This type of abundance pattern has been found by recent studies in several other metal-poor giants. We suggest that HE 1300+0157 is an unevolved example of this group of stars, which exhibit high C abundances together with low (or absent) abundances of neutron-capture elements (CEMP-no). Several potential enrichment scenarios are presented. The nondetection of neutron-capture elements including Sr, Ba, and Pb suggests that the carbon excess observed in HE 1300+0157 is not due to mass transfer across a binary system. Such a scenario is applied to carbon-rich objects with excesses of s-process elements. The normal observed Li abundance supports this interpretation. Most likely, the high levels of C and O were produced prior to the birth of this star. It remains unclear whether a single faint SN is responsible for its overall chemical pattern, or whether one requires a superposition of yields from a massive Population III object and a hypernova. These scenarios provide important information on the C production in the early universe and on the formation of C-rich stars in the early Galaxy.
Place, publisher, year, edition, pages
2007. Vol. 658, no 1, 534-552 p.
Galaxy : abundances, Galaxy : halo, stars : abundances, stars : individual (HE 1300+0157), stars : Population II
IdentifiersURN: urn:nbn:se:uu:diva-145639ISI: 000244928900046OAI: oai:DiVA.org:uu-145639DiVA: diva2:396482