Detailed Abundances for 28 Metal-poor Stars: Stellar Relics in the Milky Way

By David K. Lai, M. Bolte, Jennifer A. Johnson, S. Lucatello, Alexander Heger, S. Woosley. 2008

262 citations recorded by the source corpus.

We present the results of an abundance analysis for a sample of stars with –4 < [ Fe/H ] < − 2. The data were obtained with the HIRES spectrograph at Keck Observatory. The set includes 28 stars, with effective temperature ranging from 4800 to 6600 K. For 13 stars with [ Fe/H ] < − 2.6, including nine with [ Fe/H ] < − 3.0 and one with [ Fe/H ] = − 4.0, these are the first reported detailed abundances. For the most metal-poor star in our sample, CS 30336–049, we measure an abundance pattern that is very similar to stars in the range [ Fe/H ] ∼ − 3.5, including a normal C + N abundance. We also find that it has very low but measurable Sr and Ba, indicating some neutron-capture activity even at this low of a metallicity. We explore this issue further by examining other very neutron capture-deficient stars and find that, at the lowest levels, [Ba/Sr] exhibits the ratio of the main r-process. We also report on a new r-process-enhanced star, CS 31078–018. This star has [ Fe/H ] = − 2.85, [ Eu/Fe ] = 1.23, and [ Ba/Eu ] = − 0.51. CS 31078–018 exhibits an “actinide boost,” i.e., much higher [Th/Eu] than expected and at a similar level to CS 31082–001. Our spectra allow us to further constrain the abundance scatter at low metallicities, which we then use to fit to the zero-metallicity Type II supernova yields of Heger & Woosley (2008). We find that supernovae with progenitor masses between 10 and 20 M☉ provide the best matches to our abundances.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0a33f5db6aab17bb6a48f17ab666ddb10e97f70d

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In Astronomy and Astrophysics

1. Timothy C. Beers
2. A. Frebel
3. Martin Asplund
4. J. Norris
5. C. Sneden
6. N. Christlieb
7. A. Helmi
8. Jo Bovy

Citations in the corpus

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