Reference : The CoRoT target HD 49933 . I. Effect of the metal abundance on the mode excitation rates
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/75543
The CoRoT target HD 49933 . I. Effect of the metal abundance on the mode excitation rates
English
Samadi, R. [Observatoire de Paris, LESIA, CNRS UMR 8109, Université Pierre et Marie Curie, Université Denis Diderot, 5 pl. J. Janssen, 92195 Meudon, France]
Ludwig, H*-G [Observatoire de Paris, GEPI, CNRS UMR 8111, 5 pl. J. Janssen, 92195 Meudon, France]
Belkacem, Kevin [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie >]
Goupil, M. J. [Observatoire de Paris, LESIA, CNRS UMR 8109, Université Pierre et Marie Curie, Université Denis Diderot, 5 pl. J. Janssen, 92195 Meudon, France]
Dupret, Marc-Antoine [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie >]
1-Jan-2010
Astronomy and Astrophysics
509
15
Yes
International
[en] convection ; turbulence ; stars: oscillations ; stars: individual: HD 49933 ; Sun: helioseismology
[en] Context. Solar-like oscillations are stochastically excited by turbulent convection at the surface layers of the stars. <BR /> Aims: We study the role of the surface metal abundance on the efficiency of the stochastic driving in the case of the CoRoT target HD 49933. <BR /> Methods: We compute two 3D hydrodynamical simulations representative - in effective temperature and gravity - of the surface layers of the CoRoT target HD 49933, a star that is rather metal poor and significantly hotter than the Sun. One 3D simulation has a solar metal abundance, and the other has a surface iron-to-hydrogen, [Fe/H], abundance ten times smaller. For each 3D simulation we match an associated global 1D model, and we compute the associated acoustic modes using a theoretical model of stochastic excitation validated in the case of the Sun and α Cen A. <BR /> Results: The rate at which energy is supplied per unit time into the acoustic modes associated with the 3D simulation with [Fe/H] = -1 is found to be about three times smaller than those associated with the 3D simulation with [Fe/H] = 0. As shown here, these differences are related to the fact that low metallicity implies surface layers with a higher mean density. In turn, a higher mean density favors smaller convective velocities and hence less efficient driving of the acoustic modes. <BR /> Conclusions: Our result shows the importance of taking the surface metal abundance into account in the modeling of the mode driving by turbulent convection. A comparison with observational data is presented in a companion paper using seismic data obtained for the CoRoT target HD 49933. The CoRoT space mission, launched on December 27, 2006, has been developped and is operated by CNES, with the contribution of Austria, Belgium, Brasil, ESA, Germany and Spain.
http://hdl.handle.net/2268/75543
10.1051/0004-6361/200911867
http://adsabs.harvard.edu/abs/2010A%26A...509A..15S
http://de.arxiv.org/abs/0910.4027

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