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3-D hydrodynamic simulations of convection in A stars

Published online by Cambridge University Press:  01 August 2006

O. Kochukhov ,
B. Freytag ,
N. Piskunov  and
M. Steffen
O. Kochukhov
Affiliation:
Astronomical Observatory, Uppsala University, Box 515, 751 20, Uppsala, Sweden
B. Freytag
Affiliation:
Astronomical Observatory, Uppsala University, Box 515, 751 20, Uppsala, Sweden
N. Piskunov
Affiliation:
Astronomical Observatory, Uppsala University, Box 515, 751 20, Uppsala, Sweden
M. Steffen
Affiliation:
Astrophysikalisches Institut Potsdam, an der Sternwarte 16, 14482 Potsdam, Germany
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Abstract

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Broadening and asymmetry of spectral lines in slowly rotating late A-type stars provide evidence for high-amplitude convective motions. The properties of turbulence observed in the A-star atmospheres are not understood theoretically and contradict results of previous numerical simulations of convection. Here we describe an ongoing effort to understand the puzzling convection signatures of A stars with the help of 3-D hydrodynamic simulations. Our approach combines realistic spectrum synthesis and non-grey hydrodynamic models computed with the CO5BOLD code. We discuss these theoretical predictions and confront them with high-resolution spectra of A stars. Our models have, for the first time, succeeded in reproducing the observed profiles of weak spectral lines without introducing fudge broadening parameters.

Keywords

Convectionline: profilesradiative transferstars: atmospheres
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S239: Convection in Astrophysics , August 2006 , pp. 68 - 70
Copyright
Copyright © International Astronomical Union 2007

References

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Piskunov, N. 1992, in Stellar Magnetism, eds. Glagolevskij, Yu.V., Romanyuk, I.I., St. Petersburg, 92Google Scholar
Wedemeyer, S., Freytag, B., Steffen, M., Ludwig, H.-G., & Holweger, H. 2004, A&A 414, 1121Google Scholar