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Titolo: The potential of the variable DA white dwarf G117-B15A as a tool for fundamental physics
Autore: Corsico, AH; Benvenuto, OG; Althaus, LG; Isern, J; Garcia-Berro, E;
- Indirizzi:
- Univ Politecn Catalunya, Dept Fis Aplicada, ES-08034 Barcelona, Spain UnivPolitecn Catalunya Barcelona Spain ES-08034 -08034 Barcelona, Spain Natl Univ La Plata, Fac Ciencias Astron & Geofis, RA-1900 La Plata, Argentina Natl Univ La Plata La Plata Argentina RA-1900 A-1900 La Plata, Argentina CSIC, Inst Ciencies Espai, ES-08034 Barcelona, Spain CSIC Barcelona Spain ES-08034 Ciencies Espai, ES-08034 Barcelona, Spain
- Titolo Testata:
- NEW ASTRONOMY
fascicolo: 4,
volume: 6,
anno: 2001,
pagine: 197 - 213
- SICI:
- 1384-1092(200105)6:4<197:TPOTVD>2.0.ZU;2-8
- Fonte:
- ISI
- Lingua:
- ENG
- Soggetto:
- ZZ CETI STARS; HYDROGEN LAYER; PERIOD CHANGE; HELIUM; MODELS; AXIONS; MATTER; SEARCH; DIFFUSION; THICKNESS;
- Keywords:
- elementary particles; stars : oscillations; white dwarfs;
- Tipo documento:
- Article
- Natura:
- Periodico
- Settore Disciplinare:
- Physical, Chemical & Earth Sciences
- Citazioni:
- 62
- Recensione:
- Indirizzi per estratti:
- Indirizzo: Garcia-Berro, E Univ Politecn Catalunya, Dept Fis Aplicada, Jordi Girona Salgado S-N,ModulB-4,Campus Nord, ES-08034 Barcelona, Spain Univ Politecn Catalunya Jordi Girona Salgado S-N,Modul B-4,Campus Nord Barcelona Spain ES-08034
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- Citazione:
- A.H. Corsico et al., "The potential of the variable DA white dwarf G117-B15A as a tool for fundamental physics", NEW ASTRON, 6(4), 2001, pp. 197-213
Abstract
White dwarfs are well studied objects. The relative simplicity of their physics allows one to obtain very detailed models which can be ultimately compared with their observed properties. Among white dwarfs there are specificclasses of stars, known as ZZ-Ceti objects, which have a hydrogen-rich envelope and show periodic variations in their light curves. G117-B15A belongsto this particular set of stars. The luminosity variations have been successfully explained as due to g-mode pulsations. G117-B15A has recently claimed to be the most stable optical clock ever found, being the rate of changeof its 215.2 s period very small: P =( 2.3 +/-1.4) x 10(-15) ss(-1), with a stability comparable to that of the most stable millisecond pulsars. The rate of change of the period is closely related to its cooling timescale, which can be accurately computed. In this paper we study the pulsational properties of G117-B15A and we use the observed rate of change of the period to impose constraints on the axion emissivity and thus, to obtain a preliminary upper bound to the mass of the axion. This upper bound turns out to be 4 cos(2)beta meVat the 95% confidence level. Although there are still several observational and theoretical uncertainties, we conclude that G117-B15A is a very promising stellar object to set up constraints on particle physics. (C) 2001 Published by Elsevier Science B. V.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/06/13 alle ore 17:18:00