HST observations of the pulsating white dwarf GD 358

Autor:	Castanheira, Bárbara Garcia, Nitta, Atsuko, Kepler, Souza Oliveira, Winget, Donald Earl, Koester, Detlev
Jazyk:	angličtina
Rok vydání:	2005
Předmět:	oscillations [Stars] evolution [Stars] Fotometria estelar Espectros estelares Estrelas variaveis variables: general [Stars] white dwarfs [Stars] Anãs brancas Pulsacoes estelares Evolucao estelar Fontes ultravioletas (astronômicas) Radiação estelar Interior estelar individual: GD 358 [Stars]
Zdroj:	Repositório Institucional da UFRGS Universidade Federal do Rio Grande do Sul (UFRGS) instacron:UFRGS
Popis:	We used time-resolved ultraviolet spectroscopy obtained with the FOS and STIS spectrographs of the Hubble Space Telescope (HST), together with archival IUE observations to measure the effective temperature (Teff), surface gravity (log g) and distance (d) of the pulsating DB white dwarf GD 358 with unprecedented accuracy, and to show that the temperature did not change during the 1996 sforzando, when the star changed basically to a single mode pulsator. We also measured for the first time for a DBV the spherical harmonic degree (l) for two modes, with k = 8 and k = 9, which was only possible because the stellar light curve was dominated by a single mode in 1996. The independent spectra provide the following values: Teff = 24 100 ± 400K, log g = 7.91 ± 0.26 and d = 42.7 ± 2.5 pc. The ultraviolet spectroscopic distance is in better agreement with the seismological value, than the one derived by parallax.
Databáze:	OpenAIRE
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