METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS
We present a comprehensive abundance analysis of two newly discovered carbon-enhanced metal-poor (CEMP) stars. HE 2138?3336 is a s-process-rich star with [Fe/H] = -2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if non-local thermodynamic equilibrium corrections are included ([P...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | en_US |
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IOP Publishing
2014
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| Online Access: | http://hdl.handle.net/1721.1/88432 https://orcid.org/0000-0002-2139-7145 |
| _version_ | 1811097766610337792 |
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| author | Placco, Vinicius M. Beers, Timothy C. Karakas, Amanda I. Kennedy, Catherine R. Rossi, Silvia Christlieb, N. Stancliffe, Richard J. Frebel, Anna L. |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Placco, Vinicius M. Beers, Timothy C. Karakas, Amanda I. Kennedy, Catherine R. Rossi, Silvia Christlieb, N. Stancliffe, Richard J. Frebel, Anna L. |
| author_sort | Placco, Vinicius M. |
| collection | MIT |
| description | We present a comprehensive abundance analysis of two newly discovered carbon-enhanced metal-poor (CEMP) stars. HE 2138?3336 is a s-process-rich star with [Fe/H] = -2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if non-local thermodynamic equilibrium corrections are included ([Pb/Fe] = +3.84). HE 2258?6358, with [Fe/H] = -2.67, exhibits enrichments in both s- and r-process elements. These stars were selected from a sample of candidate metal-poor stars from the Hamburg/ESO objective-prism survey, and followed up with medium-resolution (R ~ 2000) spectroscopy with GEMINI/GMOS. We report here on derived abundances (or limits) for a total of 34 elements in each star, based on high-resolution (R ~ 30, 000) spectroscopy obtained with Magellan-Clay/MIKE. Our results are compared to predictions from new theoretical asymptotic giant branch (AGB) nucleosynthesis models of 1.3? M [subscript ?] with [Fe/H] = ?2.5 and ?2.8, as well as to a set of AGB models of 1.0 to 6.0?M [subscript ?] at [Fe/H] = ?2.3. The agreement with the model predictions suggests that the neutron-capture material in HE 2138?3336 originated from mass transfer from a binary companion star that previously went through the AGB phase, whereas for HE 2258?6358, an additional process has to be taken into account to explain its abundance pattern. We find that a narrow range of progenitor masses (1.0 ? M(M [subscript ?]) ? 1.3) and metallicities (?2.8 ? [Fe/H] ??2.5) yield the best agreement with our observed elemental abundance patterns. |
| first_indexed | 2024-09-23T17:04:35Z |
| format | Article |
| id | mit-1721.1/88432 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T17:04:35Z |
| publishDate | 2014 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/884322022-10-03T10:13:18Z METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS Placco, Vinicius M. Beers, Timothy C. Karakas, Amanda I. Kennedy, Catherine R. Rossi, Silvia Christlieb, N. Stancliffe, Richard J. Frebel, Anna L. Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Frebel, Anna L. We present a comprehensive abundance analysis of two newly discovered carbon-enhanced metal-poor (CEMP) stars. HE 2138?3336 is a s-process-rich star with [Fe/H] = -2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if non-local thermodynamic equilibrium corrections are included ([Pb/Fe] = +3.84). HE 2258?6358, with [Fe/H] = -2.67, exhibits enrichments in both s- and r-process elements. These stars were selected from a sample of candidate metal-poor stars from the Hamburg/ESO objective-prism survey, and followed up with medium-resolution (R ~ 2000) spectroscopy with GEMINI/GMOS. We report here on derived abundances (or limits) for a total of 34 elements in each star, based on high-resolution (R ~ 30, 000) spectroscopy obtained with Magellan-Clay/MIKE. Our results are compared to predictions from new theoretical asymptotic giant branch (AGB) nucleosynthesis models of 1.3? M [subscript ?] with [Fe/H] = ?2.5 and ?2.8, as well as to a set of AGB models of 1.0 to 6.0?M [subscript ?] at [Fe/H] = ?2.3. The agreement with the model predictions suggests that the neutron-capture material in HE 2138?3336 originated from mass transfer from a binary companion star that previously went through the AGB phase, whereas for HE 2258?6358, an additional process has to be taken into account to explain its abundance pattern. We find that a narrow range of progenitor masses (1.0 ? M(M [subscript ?]) ? 1.3) and metallicities (?2.8 ? [Fe/H] ??2.5) yield the best agreement with our observed elemental abundance patterns. National Science Foundation (U.S.) 2014-07-18T13:55:12Z 2014-07-18T13:55:12Z 2013-05 2013-01 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/88432 Placco, Vinicius M., Anna Frebel, Timothy C. Beers, Amanda I. Karakas, Catherine R. Kennedy, Silvia Rossi, Norbert Christlieb, and Richard J. Stancliffe. “METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS.” The Astrophysical Journal 770, no. 2 (June 20, 2013): 104. https://orcid.org/0000-0002-2139-7145 en_US http://dx.doi.org/10.1088/0004-637x/770/2/104 The Astrophysical Journal Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf IOP Publishing arXiv |
| spellingShingle | Placco, Vinicius M. Beers, Timothy C. Karakas, Amanda I. Kennedy, Catherine R. Rossi, Silvia Christlieb, N. Stancliffe, Richard J. Frebel, Anna L. METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS |
| title | METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS |
| title_full | METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS |
| title_fullStr | METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS |
| title_full_unstemmed | METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS |
| title_short | METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS |
| title_sort | metal poor stars observed with the magellan telescope i constraints on progenitor mass and metallicity of agb stars undergoing s process nucleosynthesis |
| url | http://hdl.handle.net/1721.1/88432 https://orcid.org/0000-0002-2139-7145 |
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