Whole Earth Telescope observations of the DBV white dwarf GD 358

• Autor(a) principal: Winget, Donald Earl
• Data de Publicação: 1994
• Outros Autores: Nather, R. Edward, Clemens, J. Christopher, Provencal, Judith L., Kleinman, Scot James, Bradley, Paul A., Claver, C.F., Dixson, James S., Montgomery, Michael Houston, Hansen, Carl J., Hine, B.P., Birch, P., Candy, M., Marar, T.M. Krishnan, Seetha, S., Ashoka, B.N., Leibowitz, Elia M., O'Donoghue, Darragh, Warner, B., Buckley, David A.H., Tripe, P., Vauclair, Gérard, Dolez, Noël, Chevreton, Michel, Serre, T., Garrido, R., Kepler, Souza Oliveira, Kanaan Neto, Antonio Nemer, Augusteijn, T., Wood, Matthew A., Bergeron, Pierre, Grauer, Albert D.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/108838
• topic: Astrofisica estelar; Observações astronômicas no visível; Pulsacoes estelares; Fotometria estelar; Estrelas variaveis; Anãs brancas; Stars: individual (GD 358); Stars: oscillations; White dwarfs

We report on the analysis of 154 hours of early continuous high-speed photometry on the pulsating DB white dwarf (DBV) GD 358, obtained during the Whole Earth Telescope (WET) run of 1990 May. The power spectrum of the light curve is dominated by power in the range from 1000 to 2400 μHz, with more than 180 significant peaks in the total spectrum. We identify ali of the triplet frequencies as degree l = 1, and from the details of their spacings we derive the total stellar mass as 0.61 ± 0.03 Mʘ , the mass of the outer helium envelope as 2.0 ± 1.0 x 10-6 M*, the absolute luminosity as 0.050 ± 0.012 Lʘ and the distance as 42 ± 3 pc. We find strong evidence for differential rotation in the radial direction−the outer envelope is rotating at least 1.8 times faster than the core−and we detect the presence of a weak magnetic field with a strength of 1300 ± 300 G. We also find a significant power at the sums and differences of the dominant frequencies, indi­ cating nonlinear processes are significant, but they have a richness and complexity that rules out resonant mode coupling as a major cause.