NLTE Analysis of High-Resolution <i>H</i>-Band Spectra, V: Neutral Sodium
In order to derive sodium abundances and investigate the effects of non-local thermodynamic equilibrium (NLTE) on the formation of <i>H</i>-band Na I lines, we update the sodium atomic model by incorporating collision rates with hydrogen from new quantum-mechanical calculations. The diff...
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MDPI AG
2023-10-01
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| Online Access: | https://www.mdpi.com/2218-1997/9/11/457 |
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| author | Zeming Zhou Jianrong Shi Shaolan Bi Hongliang Yan Junbo Zhang Kaike Pan Xiaodong Xu |
| author_facet | Zeming Zhou Jianrong Shi Shaolan Bi Hongliang Yan Junbo Zhang Kaike Pan Xiaodong Xu |
| author_sort | Zeming Zhou |
| collection | DOAJ |
| description | In order to derive sodium abundances and investigate the effects of non-local thermodynamic equilibrium (NLTE) on the formation of <i>H</i>-band Na I lines, we update the sodium atomic model by incorporating collision rates with hydrogen from new quantum-mechanical calculations. The differential Na abundances for 13 sample stars are obtained by analyzing high-resolution <i>H</i>-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and optical spectra under both local thermodynamic equilibrium (LTE) and NLTE conditions. Consistent abundances from both bands suggest that our updated atomic model is valid for studying the formation of <i>H</i>-band Na I lines. Our calculations show that, in our stellar parameter space, NLTE effects are negative and can result in corrections larger than −0.4 dex on optical lines. The corrections on <i>H</i>-band Na I lines are typically small, within about 0.05 dex, but not negligible if accurate sodium abundance is desired. We note that the [Na/Fe] ratios favor the theoretical galactic chemical model. |
| first_indexed | 2024-03-09T16:23:39Z |
| format | Article |
| id | doaj.art-73398996ae0641a0bfe2230c8faeaf47 |
| institution | Directory Open Access Journal |
| issn | 2218-1997 |
| language | English |
| last_indexed | 2024-03-09T16:23:39Z |
| publishDate | 2023-10-01 |
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| series | Universe |
| spelling | doaj.art-73398996ae0641a0bfe2230c8faeaf472023-11-24T15:09:45ZengMDPI AGUniverse2218-19972023-10-0191145710.3390/universe9110457NLTE Analysis of High-Resolution <i>H</i>-Band Spectra, V: Neutral SodiumZeming Zhou0Jianrong Shi1Shaolan Bi2Hongliang Yan3Junbo Zhang4Kaike Pan5Xiaodong Xu6Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, ChinaCAS Key Laboratory of Optical Astronomy, National Astronomical Observotories, Chinese Academy of Sciences, Beijing 100101, ChinaInstitute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, ChinaInstitute for Frontiers in Astronomy and Astrophysics, Beijing Normal University, Beijing 102206, ChinaCAS Key Laboratory of Optical Astronomy, National Astronomical Observotories, Chinese Academy of Sciences, Beijing 100101, ChinaApache Point Observotory, Sunspot, NM 88349, USACollege of Physics and Electronic Information, Dezhou University, Shandong 253023, ChinaIn order to derive sodium abundances and investigate the effects of non-local thermodynamic equilibrium (NLTE) on the formation of <i>H</i>-band Na I lines, we update the sodium atomic model by incorporating collision rates with hydrogen from new quantum-mechanical calculations. The differential Na abundances for 13 sample stars are obtained by analyzing high-resolution <i>H</i>-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and optical spectra under both local thermodynamic equilibrium (LTE) and NLTE conditions. Consistent abundances from both bands suggest that our updated atomic model is valid for studying the formation of <i>H</i>-band Na I lines. Our calculations show that, in our stellar parameter space, NLTE effects are negative and can result in corrections larger than −0.4 dex on optical lines. The corrections on <i>H</i>-band Na I lines are typically small, within about 0.05 dex, but not negligible if accurate sodium abundance is desired. We note that the [Na/Fe] ratios favor the theoretical galactic chemical model.https://www.mdpi.com/2218-1997/9/11/457line: formationline: profilesstars: abundancesstars: atmospheres |
| spellingShingle | Zeming Zhou Jianrong Shi Shaolan Bi Hongliang Yan Junbo Zhang Kaike Pan Xiaodong Xu NLTE Analysis of High-Resolution <i>H</i>-Band Spectra, V: Neutral Sodium Universe line: formation line: profiles stars: abundances stars: atmospheres |
| title | NLTE Analysis of High-Resolution <i>H</i>-Band Spectra, V: Neutral Sodium |
| title_full | NLTE Analysis of High-Resolution <i>H</i>-Band Spectra, V: Neutral Sodium |
| title_fullStr | NLTE Analysis of High-Resolution <i>H</i>-Band Spectra, V: Neutral Sodium |
| title_full_unstemmed | NLTE Analysis of High-Resolution <i>H</i>-Band Spectra, V: Neutral Sodium |
| title_short | NLTE Analysis of High-Resolution <i>H</i>-Band Spectra, V: Neutral Sodium |
| title_sort | nlte analysis of high resolution i h i band spectra v neutral sodium |
| topic | line: formation line: profiles stars: abundances stars: atmospheres |
| url | https://www.mdpi.com/2218-1997/9/11/457 |
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