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Towards a pure ZZ Ceti instability strip

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Towards a pure ZZ Ceti instability strip

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Título Towards a pure ZZ Ceti instability strip
Autor Castanheira, Bárbara Garcia
Kepler, Souza Oliveira
Costa, Alex Fabiano Murillo da
Giovannini Junior, Odilon
Robinson, E.L.
Winget, Donald Earl
Kleinman, Scot James
Nitta, Atsuko
Eisenstein, D.J.
Koester, Detlev
Santos, Marcio Gabriel dos
Abstract Context. We have observed again two stars inside the ZZ Ceti instability strip that were previously classified as not-observed-to-vary (NOV) by Mukadam et al. (2004) and found them to be low-amplitude variables. Some evidence points to a pure ZZ Ceti instability strip; other evidence contests it. Aims. The two stars previously classified as NOV have Sloan Digital Sky Survey (SDSS) spectroscopic effective temperatures that place them inside the ZZ Ceti instability strip, and they were “contaminating” the strip as constant stars, which could indicate that the instability strip was no longer a simple evolutionary stage. A pure instability strip indicates that pulsation is a normal phase which all DAs must go through. Methods. We used effective temperatures derived from SDSS optical spectra by comparing them with model atmospheres to look for pulsators through time-resolved photometry and stars previously classified as NOV. Results. Our new results indicate, but do not prove, a pure instability strip, because there are still other NOV stars that need to be observed again. Additionally, we have discovered five other ZZ Ceti stars based on their effective temperatures.
Contido em Astronomy and astrophysics. Vol. 462, no. 3 (Feb. 2007), p. 989-993
Assunto Anãs brancas
Estrelas
Oscilacoes
[en] Stars: oscillations
[en] Stars: variables: general
[en] Stars: white dwarfs
Origem Estrangeiro
Tipo Artigo de periódico
URI http://hdl.handle.net/10183/98982
Arquivos Descrição Formato
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