Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT 19868
We present an analysis of intermediate-dispersion spectra and photometric data of the newly identified cool, polluted white dwarf NLTT 19868. The spectra obtained with X-shooter on the Very Large Telescope-Melipal show strong lines of calcium, and several lines of magnesium, aluminium and iron. We u...
| Main Authors: | , |
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| Format: | Journal Article |
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Oxford University Press
2016
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| Online Access: | http://hdl.handle.net/20.500.11937/71932 |
| _version_ | 1848762613380415488 |
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| author | Kawka, Adela Vennes, S. |
| author_facet | Kawka, Adela Vennes, S. |
| author_sort | Kawka, Adela |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We present an analysis of intermediate-dispersion spectra and photometric data of the newly identified cool, polluted white dwarf NLTT 19868. The spectra obtained with X-shooter on the Very Large Telescope-Melipal show strong lines of calcium, and several lines of magnesium, aluminium and iron. We use these spectra and the optical-to-near-infrared spectral energy distribution to constrain the atmospheric parameters of NLTT 19868. Our analysis shows that NLTT 19868 is iron poor with respect to aluminium and calcium. A comparison with other cool, polluted white dwarfs shows that the Fe to Ca abundance ratio (Fe/Ca) varies by up to approximately two orders of magnitudes over a narrow temperature range with NLTT 19868 at one extremum in the Fe/Ca ratio and, in contrast, NLTT 888 at the other extremum. The sample shows evidence of extreme diversity in the composition of the accreted material: in the case of NLTT 888, the inferred composition of the accreted matter is akin to iron-rich planetary core composition, while in the case of NLTT 19868 it is close to mantle composition depleted by subsequent chemical separation at the bottom of the convection zone. |
| first_indexed | 2025-11-14T10:50:21Z |
| format | Journal Article |
| id | curtin-20.500.11937-71932 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:50:21Z |
| publishDate | 2016 |
| publisher | Oxford University Press |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-719322019-02-11T03:47:56Z Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT 19868 Kawka, Adela Vennes, S. We present an analysis of intermediate-dispersion spectra and photometric data of the newly identified cool, polluted white dwarf NLTT 19868. The spectra obtained with X-shooter on the Very Large Telescope-Melipal show strong lines of calcium, and several lines of magnesium, aluminium and iron. We use these spectra and the optical-to-near-infrared spectral energy distribution to constrain the atmospheric parameters of NLTT 19868. Our analysis shows that NLTT 19868 is iron poor with respect to aluminium and calcium. A comparison with other cool, polluted white dwarfs shows that the Fe to Ca abundance ratio (Fe/Ca) varies by up to approximately two orders of magnitudes over a narrow temperature range with NLTT 19868 at one extremum in the Fe/Ca ratio and, in contrast, NLTT 888 at the other extremum. The sample shows evidence of extreme diversity in the composition of the accreted material: in the case of NLTT 888, the inferred composition of the accreted matter is akin to iron-rich planetary core composition, while in the case of NLTT 19868 it is close to mantle composition depleted by subsequent chemical separation at the bottom of the convection zone. 2016 Journal Article http://hdl.handle.net/20.500.11937/71932 10.1093/mnras/stw383 Oxford University Press fulltext |
| spellingShingle | Kawka, Adela Vennes, S. Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT 19868 |
| title | Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT 19868 |
| title_full | Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT 19868 |
| title_fullStr | Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT 19868 |
| title_full_unstemmed | Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT 19868 |
| title_short | Extreme abundance ratios in the polluted atmosphere of the cool white dwarf NLTT 19868 |
| title_sort | extreme abundance ratios in the polluted atmosphere of the cool white dwarf nltt 19868 |
| url | http://hdl.handle.net/20.500.11937/71932 |