Pulsations powered by hydrogen shell burning in white dwarfs
Context. In the absence of a third dredge-up episode during the asymptotic giant-branch phase, white dwarf models evolved from low-metallicity progenitors have a thick hydrogen envelope, which makes hydrogen shell burning be the most important energy source. Aims. We investigate the pulsational sta...
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| Autores principales: | , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
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2016
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/85919 |
| Aporte de: |
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I19-R120-10915-85919 |
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dspace |
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Universidad Nacional de La Plata |
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I-19 |
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R-120 |
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SEDICI (UNLP) |
| language |
Inglés |
| topic |
Ciencias Astronómicas Stars: evolution Stars: interiors Stars: oscillations White dwarfs |
| spellingShingle |
Ciencias Astronómicas Stars: evolution Stars: interiors Stars: oscillations White dwarfs Camisassa, María Eugenia Córsico, Alejandro Hugo Althaus, Leandro Gabriel Shibahashi, H. Pulsations powered by hydrogen shell burning in white dwarfs |
| topic_facet |
Ciencias Astronómicas Stars: evolution Stars: interiors Stars: oscillations White dwarfs |
| description |
Context. In the absence of a third dredge-up episode during the asymptotic giant-branch phase, white dwarf models evolved from low-metallicity progenitors have a thick hydrogen envelope, which makes hydrogen shell burning be the most important energy source.
Aims. We investigate the pulsational stability of white dwarf models with thick envelopes to see whether nonradial g-mode pulsations are triggered by hydrogen burning, with the aim of placing constraints on hydrogen shell burning in cool white dwarfs and on a third dredge-up during the asymptotic giant-branch evolution of their progenitor stars.
Methods. We construct white-dwarf sequences from low-metallicity progenitors by means of full evolutionary calculations that take into account the entire history of progenitor stars, including the thermally pulsing and the post-asymptotic giant-branch phases, and analyze their pulsation stability by solving the linear, nonadiabatic, nonradial pulsation equations for the models in the range of effective temperatures T<SUB>eff</SUB> ~ 15 000-8000 K.
Results. We demonstrate that, for white dwarf models with masses M<SUB>★</SUB> ≲ 0.71 M⊙ and effective temperatures 8500 ≲ T<SUB>eff</SUB> ≲ 11 600 K that evolved from low-metallicity progenitors (Z = 0.0001, 0.0005, and 0.001), the dipole (ℓ = 1) and quadrupole (ℓ = 2) g<SUB>1</SUB>-modes are excited mostly as a result of the hydrogen-burning shell through the ϵ-mechanism, in addition to other g-modes driven by either the κ-γ or the convective driving mechanism. However, the ϵ mechanism is insufficient to drive these modes in white dwarfs evolved from solar-metallicity progenitors.
Conclusions. We suggest that efforts should be made to observe the dipole g1-mode in white dwarfs associated with low-metallicity environments, such as globular clusters and/or the galactic halo, to place constraints on hydrogen shell burning in cool white dwarfs and the third dredge-up episode during the preceding asymptotic giant-branch phase. |
| format |
Articulo Articulo |
| author |
Camisassa, María Eugenia Córsico, Alejandro Hugo Althaus, Leandro Gabriel Shibahashi, H. |
| author_facet |
Camisassa, María Eugenia Córsico, Alejandro Hugo Althaus, Leandro Gabriel Shibahashi, H. |
| author_sort |
Camisassa, María Eugenia |
| title |
Pulsations powered by hydrogen shell burning in white dwarfs |
| title_short |
Pulsations powered by hydrogen shell burning in white dwarfs |
| title_full |
Pulsations powered by hydrogen shell burning in white dwarfs |
| title_fullStr |
Pulsations powered by hydrogen shell burning in white dwarfs |
| title_full_unstemmed |
Pulsations powered by hydrogen shell burning in white dwarfs |
| title_sort |
pulsations powered by hydrogen shell burning in white dwarfs |
| publishDate |
2016 |
| url |
http://sedici.unlp.edu.ar/handle/10915/85919 |
| work_keys_str_mv |
AT camisassamariaeugenia pulsationspoweredbyhydrogenshellburninginwhitedwarfs AT corsicoalejandrohugo pulsationspoweredbyhydrogenshellburninginwhitedwarfs AT althausleandrogabriel pulsationspoweredbyhydrogenshellburninginwhitedwarfs AT shibahashih pulsationspoweredbyhydrogenshellburninginwhitedwarfs |
| bdutipo_str |
Repositorios |
| _version_ |
1764820489113436160 |