The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14*
We present a detailed abundance analysis of the bright (V = 9.02), metal-poor ([Fe/H] = -1.47 ± 0.08) field red horizontal-branch star HD 222925, which was observed as part of an ongoing survey by the R-Process Alliance. We calculate stellar parameters and derive abundances for 46 elements based on...
| Main Authors: | , , , , , , |
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| Format: | Article |
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American Astronomical Society
2020
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| Online Access: | https://hdl.handle.net/1721.1/124740 |
| _version_ | 1826215660090294272 |
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| author | Roederer, Ian U. Sakari, Charli M. Placco, Vinicius M. Beers, Timothy C. Ezzeddine, Rana Frebel, Anna Hansen, Terese T. |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Roederer, Ian U. Sakari, Charli M. Placco, Vinicius M. Beers, Timothy C. Ezzeddine, Rana Frebel, Anna Hansen, Terese T. |
| author_sort | Roederer, Ian U. |
| collection | MIT |
| description | We present a detailed abundance analysis of the bright (V = 9.02), metal-poor ([Fe/H] = -1.47 ± 0.08) field red horizontal-branch star HD 222925, which was observed as part of an ongoing survey by the R-Process Alliance. We calculate stellar parameters and derive abundances for 46 elements based on 901 lines examined in a high-resolution optical spectrum obtained using the Magellan Inamori Kyocera Echelle spectrograph. We detect 28 elements with 38 ≤ Z ≤ 90; their abundance pattern is a close match to the solar r-process component. The distinguishing characteristic of HD 222925 is an extreme enhancement of r-process elements ([Eu/Fe] = +1.33 ± 0.08, [Ba/Eu] = -0.78 ± 0.10) in a moderately metal-poor star, so the abundance of r-process elements is the highest ([Eu/H] = -0.14 ± 0.09) in any known r-process-enhanced star. The abundance ratios among lighter (Z ≤ 30) elements are typical for metal-poor stars, indicating that production of these elements was dominated by normal Type II supernovae, with no discernible contributions from Type Ia supernovae or asymptotic giant branch stars. The chemical and kinematic properties of HD 222925 suggest it formed in a low-mass dwarf galaxy, which was enriched by a high-yield r-process event before being disrupted by interaction with the Milky Way. ©2018 |
| first_indexed | 2024-09-23T16:37:26Z |
| format | Article |
| id | mit-1721.1/124740 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T16:37:26Z |
| publishDate | 2020 |
| publisher | American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/1247402024-06-21T13:07:54Z The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14* Roederer, Ian U. Sakari, Charli M. Placco, Vinicius M. Beers, Timothy C. Ezzeddine, Rana Frebel, Anna Hansen, Terese T. Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research We present a detailed abundance analysis of the bright (V = 9.02), metal-poor ([Fe/H] = -1.47 ± 0.08) field red horizontal-branch star HD 222925, which was observed as part of an ongoing survey by the R-Process Alliance. We calculate stellar parameters and derive abundances for 46 elements based on 901 lines examined in a high-resolution optical spectrum obtained using the Magellan Inamori Kyocera Echelle spectrograph. We detect 28 elements with 38 ≤ Z ≤ 90; their abundance pattern is a close match to the solar r-process component. The distinguishing characteristic of HD 222925 is an extreme enhancement of r-process elements ([Eu/Fe] = +1.33 ± 0.08, [Ba/Eu] = -0.78 ± 0.10) in a moderately metal-poor star, so the abundance of r-process elements is the highest ([Eu/H] = -0.14 ± 0.09) in any known r-process-enhanced star. The abundance ratios among lighter (Z ≤ 30) elements are typical for metal-poor stars, indicating that production of these elements was dominated by normal Type II supernovae, with no discernible contributions from Type Ia supernovae or asymptotic giant branch stars. The chemical and kinematic properties of HD 222925 suggest it formed in a low-mass dwarf galaxy, which was enriched by a high-yield r-process event before being disrupted by interaction with the Milky Way. ©2018 NSF (grant no. PHY 14-30152) NSF (grant no. AST-1716251) 2020-04-17T20:16:24Z 2020-04-17T20:16:24Z 2018-10 2018-07 2019-03-22T15:46:11Z Article http://purl.org/eprint/type/JournalArticle 1538-4357 https://hdl.handle.net/1721.1/124740 Roederer, Ian U., et al., "The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14*." Astrophysical journal 865, 2 (October 2018): no. 129 doi 10.3847/1538-4357/AADD92 ©2018 Author(s) 10.3847/1538-4357/AADD92 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 American Astronomical Society The Astrophysical Journal |
| spellingShingle | Roederer, Ian U. Sakari, Charli M. Placco, Vinicius M. Beers, Timothy C. Ezzeddine, Rana Frebel, Anna Hansen, Terese T. The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14* |
| title | The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14* |
| title_full | The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14* |
| title_fullStr | The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14* |
| title_full_unstemmed | The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14* |
| title_short | The R-Process Alliance: a comprehensive abundance analysis of HD 222925, a metal-poor star with an extreme R-process enhancement of [Eu/H] = −0.14* |
| title_sort | r process alliance a comprehensive abundance analysis of hd 222925 a metal poor star with an extreme r process enhancement of eu h 0 14 |
| url | https://hdl.handle.net/1721.1/124740 |
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