EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS
We present an elemental abundance analysis for four newly discovered ultra metal-poor stars from the Hamburg/ESO survey, with [Fe/H] ≤ –4. Based on high-resolution, high signal-to-noise spectra, we derive abundances for 17 elements in the range from Li to Ba. Three of the four stars exhibit moderate...
| Main Authors: | , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/94583 https://orcid.org/0000-0002-2139-7145 |
| _version_ | 1811089357752238080 |
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| author | Hansen, T. Hansen, C. J. Christlieb, N. Yong, D. Bessell, M. S. Beers, Timothy C. Placco, V. M. Norris, J. E. Asplund, M. Frebel, Anna L. Garcia Perez, A. E. |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Hansen, T. Hansen, C. J. Christlieb, N. Yong, D. Bessell, M. S. Beers, Timothy C. Placco, V. M. Norris, J. E. Asplund, M. Frebel, Anna L. Garcia Perez, A. E. |
| author_sort | Hansen, T. |
| collection | MIT |
| description | We present an elemental abundance analysis for four newly discovered ultra metal-poor stars from the Hamburg/ESO survey, with [Fe/H] ≤ –4. Based on high-resolution, high signal-to-noise spectra, we derive abundances for 17 elements in the range from Li to Ba. Three of the four stars exhibit moderate to large overabundances of carbon, but have no enhancements in their neutron-capture elements. The most metal-poor star in the sample, HE 0233–0343 ([Fe/H] = –4.68), is a subgiant with a carbon enhancement of [C/Fe] = +3.5, slightly above the carbon-enhancement plateau suggested by Spite et al. No carbon is detected in the spectrum of the fourth star, but the quality of its spectrum only allows for the determination of an upper limit on the carbon abundance ratio of [C/Fe] < +1.7. We detect lithium in the spectra of two of the carbon-enhanced stars, including HE 0233–0343. Both stars with Li detections are Li-depleted, with respect to the Li plateau for metal-poor dwarfs found by Spite & Spite. This suggests that whatever site(s) produced C either do not completely destroy lithium, or that Li has been astrated by early-generation stars and mixed with primordial Li in the gas that formed the stars observed at present. The derived abundances for the α elements and iron-peak elements of the four stars are similar to those found in previous large samples of extremely and ultra metal-poor stars. Finally, a large spread is found in the abundances of Sr and Ba for these stars, possibly influenced by enrichment from fast rotating stars in the early universe. |
| first_indexed | 2024-09-23T14:17:53Z |
| format | Article |
| id | mit-1721.1/94583 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T14:17:53Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/945832022-10-01T20:26:39Z EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS Hansen, T. Hansen, C. J. Christlieb, N. Yong, D. Bessell, M. S. Beers, Timothy C. Placco, V. M. Norris, J. E. Asplund, M. Frebel, Anna L. Garcia Perez, A. E. Massachusetts Institute of Technology. Department of Physics Frebel, Anna L. We present an elemental abundance analysis for four newly discovered ultra metal-poor stars from the Hamburg/ESO survey, with [Fe/H] ≤ –4. Based on high-resolution, high signal-to-noise spectra, we derive abundances for 17 elements in the range from Li to Ba. Three of the four stars exhibit moderate to large overabundances of carbon, but have no enhancements in their neutron-capture elements. The most metal-poor star in the sample, HE 0233–0343 ([Fe/H] = –4.68), is a subgiant with a carbon enhancement of [C/Fe] = +3.5, slightly above the carbon-enhancement plateau suggested by Spite et al. No carbon is detected in the spectrum of the fourth star, but the quality of its spectrum only allows for the determination of an upper limit on the carbon abundance ratio of [C/Fe] < +1.7. We detect lithium in the spectra of two of the carbon-enhanced stars, including HE 0233–0343. Both stars with Li detections are Li-depleted, with respect to the Li plateau for metal-poor dwarfs found by Spite & Spite. This suggests that whatever site(s) produced C either do not completely destroy lithium, or that Li has been astrated by early-generation stars and mixed with primordial Li in the gas that formed the stars observed at present. The derived abundances for the α elements and iron-peak elements of the four stars are similar to those found in previous large samples of extremely and ultra metal-poor stars. Finally, a large spread is found in the abundances of Sr and Ba for these stars, possibly influenced by enrichment from fast rotating stars in the early universe. German Research Foundation (Sonderforschungsbereich SFB 881 “The Milky Way System” (subproject A4)) National Science Foundation (U.S.) (Grant AST-1255160) 2015-02-18T16:08:07Z 2015-02-18T16:08:07Z 2014-05 2013-11 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/94583 Hansen, T., C. J. Hansen, N. Christlieb, D. Yong, M. S. Bessell, A. E. Garcia Perez, T. C. Beers, et al. “EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS.” The Astrophysical Journal 787, no. 2 (June 1, 2014): 162. © 2014 The American Astronomical Society https://orcid.org/0000-0002-2139-7145 en_US http://dx.doi.org/10.1088/0004-637X/787/2/162 The Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing American Astronomical Society |
| spellingShingle | Hansen, T. Hansen, C. J. Christlieb, N. Yong, D. Bessell, M. S. Beers, Timothy C. Placco, V. M. Norris, J. E. Asplund, M. Frebel, Anna L. Garcia Perez, A. E. EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS |
| title | EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS |
| title_full | EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS |
| title_fullStr | EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS |
| title_full_unstemmed | EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS |
| title_short | EXPLORING THE ORIGIN OF LITHIUM, CARBON, STRONTIUM, AND BARIUM WITH FOUR NEW ULTRA METAL-POOR STARS |
| title_sort | exploring the origin of lithium carbon strontium and barium with four new ultra metal poor stars |
| url | http://hdl.handle.net/1721.1/94583 https://orcid.org/0000-0002-2139-7145 |
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