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2006 Whole Earth Telescope observations of GD358 : a new look at the prototype DBV

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2006 Whole Earth Telescope observations of GD358 : a new look at the prototype DBV

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Título 2006 Whole Earth Telescope observations of GD358 : a new look at the prototype DBV
Autor Provencal, Judith L.
Montgomery, Michael Houston
Kanaan Neto, Antonio Nemer
Shipman, Harry L.
Childers, D.
Baran, Andrzej
Kepler, Souza Oliveira
Reed, M. D.
Zhou, Ai-Ying
Eggen, J.
Watson, Todd K.
Winget, Donald Earl
Thompson, S. E.
Riaz, B.
Nitta, Atsuko
Kleinman, Scot James
Crowe, Richard A.
Slivkoff, Jay
Sherard, P.
Purves, Norman G.
Binder, Philippe M.
Knight, R.
Kim, Seung-Lee
Chen, Wen-Ping
Yang, M.
Lin, Hung-Chin
Lin, Chien-Cheng
Chen, C.-W.
Jiang, Xiaojun
Sergeev, A.
Mkrtichian, David
Andreev, M.
Janulis, Rimvydas
Siwak, Michal
Zola, Staszek
Koziel-Wierzbowska, Dorota
Stachowski, G.
Paparo, Margit
Bognár, Zsófia
Handler, Gerald
Lorenz, Denise
Steininger, Bruno
Beck, Paul
Nagel, Thorsten
Kusterer, D.
Hoffman, A.
Reiff, E.
Kowalski, R.
Vauclair, Gérard
Charpinet, Stéphane
Chevreton, Michel
Solheim, Jan-Eric
Pakstiene, Erika
Fraga, Luciano
Dalessio, J.
Abstract We report on the analysis of 436.1 hr of nearly continuous high-speed photometry on the pulsating DB white dwarf GD358 acquired with the Whole Earth Telescope (WET) during the 2006 international observing run, designated XCOV25. The Fourier transform (FT) of the light curve contains power between 1000 and 4000 μHz, with the dominant peak at 1234 μHz. We find 27 independent frequencies distributed in 10 modes, as well as numerous combination frequencies. Our discussion focuses on a new asteroseismological analysis of GD358, incorporating the 2006 data set and drawing on 24 years of archival observations. Our results reveal that, while the general frequency locations of the identified modes are consistent throughout the years, the multiplet structure is complex and cannot be interpreted simply as l =l modes in the limit of slow rotation. The high-k multiplets exhibit significant variability in structure, amplitude and frequency. Any identification of the m components for the high-k multiplets is highly suspect. The k = 9 and 8 modes typically do show triplet structure more consistent with theoretical expectations. The frequencies and amplitudes exhibit some variability, but much less than the high-k modes. Analysis of the k = 9 and 8 multiplet splittings from 1990 to 2008 reveal a long-term change in multiplet splittings coinciding with the 1996 sforzando event, where GD358 dramatically altered its pulsation characteristics on a timescale of hours. We explore potential implications, including the possible connections between convection and/or magnetic fields and pulsations.We suggest future investigations, including theoretical investigations of the relationship between magnetic fields, pulsation, growth rates, and convection.
Contido em The astrophysical journal. Bristol. Vol. 693, no. 1 (Mar. 2009), p. 564-585
Assunto Anãs brancas
Dinâmica de fluidos astrofísicos
Espectros estelares
Estrelas variaveis
Estrutura estelar
Evolucao estelar
Magnetismo estelar
Pulsacoes estelares
Radiação estelar
[en] Stars: evolution
[en] Stars: individual (GD358)
[en] Stars: oscillations
[en] White dwarfs
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/108971
Arquivos Descrição Formato
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