Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections
To calculate realistic models of objects with Ni in their atmospheres, accurate atomic data for the relevant ionization stages need to be included in model atmosphere calculations. In the context of white dwarf stars, we investigate the effect of changing the Ni IV-VI bound-bound and bound-free atom...
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OXFORD UNIV PRESS
2017
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ndltd-arizona.edu-oai-arizona.openrepository.com-10150-6230442017-04-08T03:00:37Z Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections Preval, S. P. Barstow, M. A. Badnell, N. R. Hubeny, I. Holberg, J. B. Univ Arizona, Steward Observ Univ Arizona, Lunar & Planetary Lab, Sonett Space Sci Bldg atomic data opacity white dwarfs To calculate realistic models of objects with Ni in their atmospheres, accurate atomic data for the relevant ionization stages need to be included in model atmosphere calculations. In the context of white dwarf stars, we investigate the effect of changing the Ni IV-VI bound-bound and bound-free atomic data on model atmosphere calculations. Models including photoionization cross-section (PICS) calculated with AUTOSTRUCTURE show significant flux attenuation of up to similar to 80 per cent shortward of 180 angstrom in the extreme ultraviolet (EUV) region compared to a model using hydrogenic PICS. Comparatively, models including a larger set of Ni transitions left the EUV, UV, and optical continua unaffected. We use models calculated with permutations of these atomic data to test for potential changes to measured metal abundances of the hot DA white dwarf G191-B2B. Models including AUTOSTRUCTURE PICS were found to change the abundances of N and O by as much as similar to 22 per cent compared to models using hydrogenic PICS, but heavier species were relatively unaffected. Models including AUTOSTRUCTURE PICS caused the abundances of N/O IV and V to diverge. This is because the increased opacity in the AUTOSTRUCTURE PICS model causes these charge states to form higher in the atmosphere, more so for N/O V. Models using an extended line list caused significant changes to the Ni IV-V abundances. While both PICS and an extended line list cause changes in both synthetic spectra and measured abundances, the biggest changes are caused by using AUTOSTRUCTURE PICS for Ni. 2017-02-11 Article Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections 2017, 465 (1):269 Monthly Notices of the Royal Astronomical Society 0035-8711 1365-2966 10.1093/mnras/stw2800 http://hdl.handle.net/10150/623044 http://arizona.openrepository.com/arizona/handle/10150/623044 Monthly Notices of the Royal Astronomical Society en https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stw2800 © 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. OXFORD UNIV PRESS |
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en |
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atomic data opacity white dwarfs |
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atomic data opacity white dwarfs Preval, S. P. Barstow, M. A. Badnell, N. R. Hubeny, I. Holberg, J. B. Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections |
description |
To calculate realistic models of objects with Ni in their atmospheres, accurate atomic data for the relevant ionization stages need to be included in model atmosphere calculations. In the context of white dwarf stars, we investigate the effect of changing the Ni IV-VI bound-bound and bound-free atomic data on model atmosphere calculations. Models including photoionization cross-section (PICS) calculated with AUTOSTRUCTURE show significant flux attenuation of up to similar to 80 per cent shortward of 180 angstrom in the extreme ultraviolet (EUV) region compared to a model using hydrogenic PICS. Comparatively, models including a larger set of Ni transitions left the EUV, UV, and optical continua unaffected. We use models calculated with permutations of these atomic data to test for potential changes to measured metal abundances of the hot DA white dwarf G191-B2B. Models including AUTOSTRUCTURE PICS were found to change the abundances of N and O by as much as similar to 22 per cent compared to models using hydrogenic PICS, but heavier species were relatively unaffected. Models including AUTOSTRUCTURE PICS caused the abundances of N/O IV and V to diverge. This is because the increased opacity in the AUTOSTRUCTURE PICS model causes these charge states to form higher in the atmosphere, more so for N/O V. Models using an extended line list caused significant changes to the Ni IV-V abundances. While both PICS and an extended line list cause changes in both synthetic spectra and measured abundances, the biggest changes are caused by using AUTOSTRUCTURE PICS for Ni. |
author2 |
Univ Arizona, Steward Observ |
author_facet |
Univ Arizona, Steward Observ Preval, S. P. Barstow, M. A. Badnell, N. R. Hubeny, I. Holberg, J. B. |
author |
Preval, S. P. Barstow, M. A. Badnell, N. R. Hubeny, I. Holberg, J. B. |
author_sort |
Preval, S. P. |
title |
Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections |
title_short |
Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections |
title_full |
Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections |
title_fullStr |
Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections |
title_full_unstemmed |
Hot DA white dwarf model atmosphere calculations: including improved Ni PI cross-sections |
title_sort |
hot da white dwarf model atmosphere calculations: including improved ni pi cross-sections |
publisher |
OXFORD UNIV PRESS |
publishDate |
2017 |
url |
http://hdl.handle.net/10150/623044 http://arizona.openrepository.com/arizona/handle/10150/623044 |
work_keys_str_mv |
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1718436513002291200 |