THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY
We present chemical abundance measurements of two metal-poor red giant stars in the ultra-faint dwarf galaxy Boötes I, based on Magellan/MIKE high-resolution spectra. For Boo-980, with Fe/H = - 3.1, we present the first elemental abundance measurements, while Boo-127, with Fe/H = - 2.0, shows abunda...
| Main Authors: | , , , |
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IOP Publishing
2018
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| Online Access: | http://hdl.handle.net/1721.1/114026 https://orcid.org/0000-0002-2139-7145 |
| _version_ | 1811086605187809280 |
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| author | Norris, John E. Gilmore, Gerard Wyse, Rosemary F. G. Frebel, Anna L. |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Norris, John E. Gilmore, Gerard Wyse, Rosemary F. G. Frebel, Anna L. |
| author_sort | Norris, John E. |
| collection | MIT |
| description | We present chemical abundance measurements of two metal-poor red giant stars in the ultra-faint dwarf galaxy Boötes I, based on Magellan/MIKE high-resolution spectra. For Boo-980, with Fe/H = - 3.1, we present the first elemental abundance measurements, while Boo-127, with Fe/H = - 2.0, shows abundances in good agreement with previous measurements. Light and iron-peak element abundance ratios in the two Boötes I stars, as well as those of most other Boötes I members, collected from the literature, closely resemble those of regular metal-poor halo stars. Neutron-capture element abundances Sr and Ba are systematically lower than the main halo trend and also show a significant abundance spread. Overall, this is similar to what has been found for other ultrafaint dwarf galaxies. We apply corrections to the carbon abundances (commensurate with stellar evolutionary status) of the entire sample and find 21% of stars to be carbon-enhanced metal-poor (CEMP) stars, compared to 13% without using the carbon correction. We reassess the metallicity distribution functions for the CEMP stars and non-CEMP stars, and confirm earlier claims that CEMP stars might belong to a different, earlier population. Applying a set of abundance criteria to test to what extent Boötes I could be a surviving first galaxy suggests that it is one of the earliest assembled systems that perhaps received gas from accretion from other clouds in the system, or from swallowing a first galaxy or building block type object. This resulted in the two stellar populations observable today. |
| first_indexed | 2024-09-23T13:28:54Z |
| format | Article |
| id | mit-1721.1/114026 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T13:28:54Z |
| publishDate | 2018 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1140262022-09-28T14:31:53Z THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY Norris, John E. Gilmore, Gerard Wyse, Rosemary F. G. Frebel, Anna L. Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Frebel, Anna L. We present chemical abundance measurements of two metal-poor red giant stars in the ultra-faint dwarf galaxy Boötes I, based on Magellan/MIKE high-resolution spectra. For Boo-980, with Fe/H = - 3.1, we present the first elemental abundance measurements, while Boo-127, with Fe/H = - 2.0, shows abundances in good agreement with previous measurements. Light and iron-peak element abundance ratios in the two Boötes I stars, as well as those of most other Boötes I members, collected from the literature, closely resemble those of regular metal-poor halo stars. Neutron-capture element abundances Sr and Ba are systematically lower than the main halo trend and also show a significant abundance spread. Overall, this is similar to what has been found for other ultrafaint dwarf galaxies. We apply corrections to the carbon abundances (commensurate with stellar evolutionary status) of the entire sample and find 21% of stars to be carbon-enhanced metal-poor (CEMP) stars, compared to 13% without using the carbon correction. We reassess the metallicity distribution functions for the CEMP stars and non-CEMP stars, and confirm earlier claims that CEMP stars might belong to a different, earlier population. Applying a set of abundance criteria to test to what extent Boötes I could be a surviving first galaxy suggests that it is one of the earliest assembled systems that perhaps received gas from accretion from other clouds in the system, or from swallowing a first galaxy or building block type object. This resulted in the two stellar populations observable today. National Science Foundation (U.S.) (Grant AST-1255160) 2018-03-06T15:09:50Z 2018-03-06T15:09:50Z 2016-07 2016-03 2018-03-02T17:59:21Z Article http://purl.org/eprint/type/JournalArticle 1538-4357 0004-637X http://hdl.handle.net/1721.1/114026 Frebel, Anna, et al. “THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY.” The Astrophysical Journal 826, 2 (July 2016):110. © 2016 American Astronomical Society https://orcid.org/0000-0002-2139-7145 http://dx.doi.org/10.3847/0004-637X/826/2/110 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 Astrophysical Journal |
| spellingShingle | Norris, John E. Gilmore, Gerard Wyse, Rosemary F. G. Frebel, Anna L. THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY |
| title | THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY |
| title_full | THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY |
| title_fullStr | THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY |
| title_full_unstemmed | THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY |
| title_short | THE CHEMICAL EVOLUTION OF THE BOÖTES I ULTRA-FAINT DWARF GALAXY |
| title_sort | chemical evolution of the bootes i ultra faint dwarf galaxy |
| url | http://hdl.handle.net/1721.1/114026 https://orcid.org/0000-0002-2139-7145 |
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