HST observations of the pulsating white dwarf GD 358

• Autor(a) principal: Castanheira, Bárbara Garcia
• Data de Publicação: 2005
• Outros Autores: Nitta, Atsuko, Kepler, Souza Oliveira, Winget, Donald Earl, Koester, Detlev
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/98977
• topic: Anãs brancas; Evolucao estelar; Interior estelar; Fotometria estelar; Pulsacoes estelares; Radiação estelar; Espectros estelares; Fontes ultravioletas (astronômicas); Estrelas variaveis; Stars: white dwarfs; Stars: variables: general; Stars: oscillations; Stars: individual: GD 358; Stars: evolution

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.