HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY
The SkyMapper Southern Sky Survey is carrying out a search for the most metal-poor stars in the Galaxy. It identifies candidates by way of its unique filter set which allows for estimation of stellar atmospheric parameters. The set includes a narrow filter centered on the Ca ii K 3933 Å line, enabli...
| Main Authors: | , , , , , , , , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/98350 https://orcid.org/0000-0001-7727-1640 https://orcid.org/0000-0002-2139-7145 |
| _version_ | 1811078690116730880 |
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| author | Keller, Stefan C. Casey, Andrew R. Asplund, Martin Bessell, Michael S. Costa, Gary S. Da Lind, Karin Marino, Anna F. Norris, John E. Schmidt, Brian P. Tisserand, Patrick Walsh, Jennifer M. Yong, David Jacobson, Heather Frebel, Anna L. Pena, Jose M. Yu, QinQin |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Keller, Stefan C. Casey, Andrew R. Asplund, Martin Bessell, Michael S. Costa, Gary S. Da Lind, Karin Marino, Anna F. Norris, John E. Schmidt, Brian P. Tisserand, Patrick Walsh, Jennifer M. Yong, David Jacobson, Heather Frebel, Anna L. Pena, Jose M. Yu, QinQin |
| author_sort | Keller, Stefan C. |
| collection | MIT |
| description | The SkyMapper Southern Sky Survey is carrying out a search for the most metal-poor stars in the Galaxy. It identifies candidates by way of its unique filter set which allows for estimation of stellar atmospheric parameters. The set includes a narrow filter centered on the Ca ii K 3933 Å line, enabling a robust estimate of stellar metallicity. Promising candidates are then confirmed with spectroscopy. We present the analysis of Magellan Inamori Kyocera Echelle high-resolution spectroscopy of 122 metal-poor stars found by SkyMapper in the first two years of commissioning observations. Forty-one stars have [Fe/H] ⩽ -3.0. Nine have [Fe/H] ⩽ -3.5, with three at [Fe/H] ~ -4. A 1D LTE abundance analysis of the elements Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, Ba, and Eu shows these stars have [X/Fe] ratios typical of other halo stars. One star with low [X/Fe] values appears to be "Fe-enhanced," while another star has an extremely large [Sr/Ba] ratio: >2. Only one other star is known to have a comparable value. Seven stars are "CEMP-no" stars ([C/Fe] > 0.7, [Ba/Fe] < 0). 21 stars exhibit mild r-process element enhancements (0.3 ⩽ [Eu/Fe] < 1.0), while four stars have [Eu/Fe] ⩾ 1.0. These results demonstrate the ability to identify extremely metal-poor stars from SkyMapper photometry, pointing to increased sample sizes and a better characterization of the metal-poor tail of the halo metallicity distribution function in the future. |
| first_indexed | 2024-09-23T11:03:55Z |
| format | Article |
| id | mit-1721.1/98350 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:03:55Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/983502022-10-01T00:54:29Z HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY Keller, Stefan C. Casey, Andrew R. Asplund, Martin Bessell, Michael S. Costa, Gary S. Da Lind, Karin Marino, Anna F. Norris, John E. Schmidt, Brian P. Tisserand, Patrick Walsh, Jennifer M. Yong, David Jacobson, Heather Frebel, Anna L. Pena, Jose M. Yu, QinQin Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Jacobson, Heather Frebel, Anna L. Pena, Jose M. Walsh, Jennifer M. Yu, Qinsi The SkyMapper Southern Sky Survey is carrying out a search for the most metal-poor stars in the Galaxy. It identifies candidates by way of its unique filter set which allows for estimation of stellar atmospheric parameters. The set includes a narrow filter centered on the Ca ii K 3933 Å line, enabling a robust estimate of stellar metallicity. Promising candidates are then confirmed with spectroscopy. We present the analysis of Magellan Inamori Kyocera Echelle high-resolution spectroscopy of 122 metal-poor stars found by SkyMapper in the first two years of commissioning observations. Forty-one stars have [Fe/H] ⩽ -3.0. Nine have [Fe/H] ⩽ -3.5, with three at [Fe/H] ~ -4. A 1D LTE abundance analysis of the elements Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, Ba, and Eu shows these stars have [X/Fe] ratios typical of other halo stars. One star with low [X/Fe] values appears to be "Fe-enhanced," while another star has an extremely large [Sr/Ba] ratio: >2. Only one other star is known to have a comparable value. Seven stars are "CEMP-no" stars ([C/Fe] > 0.7, [Ba/Fe] < 0). 21 stars exhibit mild r-process element enhancements (0.3 ⩽ [Eu/Fe] < 1.0), while four stars have [Eu/Fe] ⩾ 1.0. These results demonstrate the ability to identify extremely metal-poor stars from SkyMapper photometry, pointing to increased sample sizes and a better characterization of the metal-poor tail of the halo metallicity distribution function in the future. National Science Foundation (U.S.) (Grant AST-1255160) Massachusetts Institute of Technology. Undergraduate Research Opportunities Program 2015-09-03T16:36:41Z 2015-09-03T16:36:41Z 2015-07 2015-01 Article http://purl.org/eprint/type/JournalArticle 1538-4357 0004-637X http://hdl.handle.net/1721.1/98350 Jacobson, Heather R., Stefan Keller, Anna Frebel, Andrew R. Casey, Martin Asplund, Michael S. Bessell, Gary S. Da Costa, et al. “HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY.” The Astrophysical Journal 807, no. 2 (July 9, 2015): 171. © 2015 The American Astronomical Society https://orcid.org/0000-0001-7727-1640 https://orcid.org/0000-0002-2139-7145 en_US http://dx.doi.org/10.1088/0004-637X/807/2/171 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 IOP Publishing |
| spellingShingle | Keller, Stefan C. Casey, Andrew R. Asplund, Martin Bessell, Michael S. Costa, Gary S. Da Lind, Karin Marino, Anna F. Norris, John E. Schmidt, Brian P. Tisserand, Patrick Walsh, Jennifer M. Yong, David Jacobson, Heather Frebel, Anna L. Pena, Jose M. Yu, QinQin HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY |
| title | HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY |
| title_full | HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY |
| title_fullStr | HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY |
| title_full_unstemmed | HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY |
| title_short | HIGH-RESOLUTION SPECTROSCOPIC STUDY OF EXTREMELY METAL-POOR STAR CANDIDATES FROM THE SKYMAPPER SURVEY |
| title_sort | high resolution spectroscopic study of extremely metal poor star candidates from the skymapper survey |
| url | http://hdl.handle.net/1721.1/98350 https://orcid.org/0000-0001-7727-1640 https://orcid.org/0000-0002-2139-7145 |
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