Asteroseismological constraints on the coolest GW Virginis variable star (PG 1159-type) PG 0122+200
Aims. We present an asteroseismological study of PG 0122+200, the coolest known pulsating PG 1159 (GW Vir) star. Our results are based on an augmented set of the full PG 1159 evolutionary models recently presented by Miller Bertolami & Althaus (2006). Methods. We perform extensive computations...
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| Autores principales: | , , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
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2007
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/83454 |
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I19-R120-10915-83454 |
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dspace |
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Universidad Nacional de La Plata |
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I-19 |
| repository_str |
R-120 |
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SEDICI (UNLP) |
| language |
Inglés |
| topic |
Ciencias Astronómicas Stars: evolution Stars: interiors Stars: oscillations Stars: variables: general Stars: white dwarfs |
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Ciencias Astronómicas Stars: evolution Stars: interiors Stars: oscillations Stars: variables: general Stars: white dwarfs Córsico, Alejandro Hugo Miller Bertolami, Marcelo Miguel Althaus, Leandro Gabriel Vauclair, G. Werner, K. Asteroseismological constraints on the coolest GW Virginis variable star (PG 1159-type) PG 0122+200 |
| topic_facet |
Ciencias Astronómicas Stars: evolution Stars: interiors Stars: oscillations Stars: variables: general Stars: white dwarfs |
| description |
Aims. We present an asteroseismological study of PG 0122+200, the coolest known pulsating PG 1159 (GW Vir) star. Our results are based on an augmented set of the full PG 1159 evolutionary models recently presented by Miller Bertolami & Althaus (2006).
Methods. We perform extensive computations of adiabatic g-mode pulsation periods on PG 1159 evolutionary models with stellar masses ranging from 0.530 to 0.741 M⊙. These models take into account the complete evolution of progenitor stars, through the thermally pulsing asymptotic giant branch phase and born-again episode. We constrain the stellar mass of PG 0122+200 by comparing the observed period spacing with the asymptotic period spacing and with the average of the computed period spacings. We also employ the individual observed periods to find a representative seismological model for PG 0122+200.
Results. We derive a stellar mass of 0.626 M⊙ from a comparison between the observed period spacing and the computed asymptotic period spacing, and a stellar mass of 0.567 M⊙ by comparing the observed period spacing with the average of the computed period spacing. We also find, on the basis of a period-fit procedure, an asteroseismological model representative of PG 0122+200 that is able to reproduce the observed period pattern with an average of the period differences of δΠ̄<SUB>i</SUB> = 0.88 s and a root-mean-square residual of σ<SUB>δΠi</SUB> = 1.27 s. The model has an effective temperature T<SUB>eff</SUB> = 81 500 K, a stellar mass M<SUB>*</SUB> = 0.556 M⊙, a surface gravity log g = 7.65, a stellar luminosity and radius of log(L<SUB>*</SUB>/L⊙) = 1.14 and log(R<SUB>*</SUB>/R ⊙) = -1.73, respectively, and a He-rich envelope thickness of M<SUB>env</SUB> = 1.9 × 10<SUP>-2</SUP> M⊙. We derive a seismic distance d ∼ 614 pc and a parallax π ∼ 1.6 mas. The results of the period-fit analysis carried out in this work suggest that the asteroseismological mass of PG 0122+200 could be ∼6-20% lower than hitherto thought, and in closer agreement (to within ∼5%) with the spectroscopic mass. This result suggests that a reasonable consistency between the stellar mass values obtained from spectroscopy and asteroseismology can be expected when detailed PG 1159 evolutionary models are considered. |
| format |
Articulo Articulo |
| author |
Córsico, Alejandro Hugo Miller Bertolami, Marcelo Miguel Althaus, Leandro Gabriel Vauclair, G. Werner, K. |
| author_facet |
Córsico, Alejandro Hugo Miller Bertolami, Marcelo Miguel Althaus, Leandro Gabriel Vauclair, G. Werner, K. |
| author_sort |
Córsico, Alejandro Hugo |
| title |
Asteroseismological constraints on the coolest GW Virginis variable star (PG 1159-type) PG 0122+200 |
| title_short |
Asteroseismological constraints on the coolest GW Virginis variable star (PG 1159-type) PG 0122+200 |
| title_full |
Asteroseismological constraints on the coolest GW Virginis variable star (PG 1159-type) PG 0122+200 |
| title_fullStr |
Asteroseismological constraints on the coolest GW Virginis variable star (PG 1159-type) PG 0122+200 |
| title_full_unstemmed |
Asteroseismological constraints on the coolest GW Virginis variable star (PG 1159-type) PG 0122+200 |
| title_sort |
asteroseismological constraints on the coolest gw virginis variable star (pg 1159-type) pg 0122+200 |
| publishDate |
2007 |
| url |
http://sedici.unlp.edu.ar/handle/10915/83454 |
| work_keys_str_mv |
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Repositorios |
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1764820488634236930 |