Ultra-metal-poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances
We present new ultra-metal-poor stars parameters with [Fe/H] < -4.0 based on line-by-line non-local thermodynamic equilibrium (NLTE) abundances using an up-to-date iron model atom with a new recipe for non-elastic hydrogen collision rates. We study the departures from LTE in their atmospheric p...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Article |
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IOP Publishing
2018
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| Online Access: | http://hdl.handle.net/1721.1/114959 https://orcid.org/0000-0002-2139-7145 |
| _version_ | 1826193688188944384 |
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| author | Plez, Bertrand Ezzeddine, Rana Frebel, Anna L. |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Plez, Bertrand Ezzeddine, Rana Frebel, Anna L. |
| author_sort | Plez, Bertrand |
| collection | MIT |
| description | We present new ultra-metal-poor stars parameters with [Fe/H] < -4.0 based on line-by-line non-local thermodynamic equilibrium (NLTE) abundances using an up-to-date iron model atom with a new recipe for non-elastic hydrogen collision rates. We study the departures from LTE in their atmospheric parameters and show that they can grow up to ∼1.00 dex in [Fe/H], ∼150 K in T eff and ∼0.5 dex in log g toward the lowest metallicities. Accurate NLTE atmospheric stellar parameters, in particular [Fe/H] being significantly higher, are the first step to eventually providing full NLTE abundance patterns that can be compared with Population III supernova nucleosynthesis yields to derive properties of the first stars. Overall, this maximizes the potential of these likely second-generation stars to investigate the early universe and how the chemical elements were formed. |
| first_indexed | 2024-09-23T09:43:07Z |
| format | Article |
| id | mit-1721.1/114959 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T09:43:07Z |
| publishDate | 2018 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/1149592022-09-26T13:20:40Z Ultra-metal-poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances Plez, Bertrand Ezzeddine, Rana Frebel, Anna L. Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Ezzeddine, Rana Frebel, Anna L. We present new ultra-metal-poor stars parameters with [Fe/H] < -4.0 based on line-by-line non-local thermodynamic equilibrium (NLTE) abundances using an up-to-date iron model atom with a new recipe for non-elastic hydrogen collision rates. We study the departures from LTE in their atmospheric parameters and show that they can grow up to ∼1.00 dex in [Fe/H], ∼150 K in T eff and ∼0.5 dex in log g toward the lowest metallicities. Accurate NLTE atmospheric stellar parameters, in particular [Fe/H] being significantly higher, are the first step to eventually providing full NLTE abundance patterns that can be compared with Population III supernova nucleosynthesis yields to derive properties of the first stars. Overall, this maximizes the potential of these likely second-generation stars to investigate the early universe and how the chemical elements were formed. 2018-04-25T19:45:49Z 2018-04-25T19:45:49Z 2017-10 2017-08 2018-04-23T19:38:51Z Article http://purl.org/eprint/type/JournalArticle 1538-4357 0004-637X http://hdl.handle.net/1721.1/114959 Ezzeddine, Rana et al. “Ultra-Metal-Poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances.” The Astrophysical Journal 847, 2 (October 2017): 142 © 2017 The American Astronomical Society https://orcid.org/0000-0002-2139-7145 http://dx.doi.org/10.3847/1538-4357/AA8875 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 | Plez, Bertrand Ezzeddine, Rana Frebel, Anna L. Ultra-metal-poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances |
| title | Ultra-metal-poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances |
| title_full | Ultra-metal-poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances |
| title_fullStr | Ultra-metal-poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances |
| title_full_unstemmed | Ultra-metal-poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances |
| title_short | Ultra-metal-poor Stars: Spectroscopic Determination of Stellar Atmospheric Parameters Using Iron Non-LTE Line Abundances |
| title_sort | ultra metal poor stars spectroscopic determination of stellar atmospheric parameters using iron non lte line abundances |
| url | http://hdl.handle.net/1721.1/114959 https://orcid.org/0000-0002-2139-7145 |
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