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Astron. Astrophys. 347, 243-248 (1999)


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Acoustic wave energy fluxes for late-type stars

II. Nonsolar metallicities

P. Ulmschneider 1, J. Theurer 1, Z.E. Musielak 2,3,1 and R. Kurucz 4

1 Institut für Theoretische Astrophysik der Universität Heidelberg, Tiergartenstrasse 15, D-69121 Heidelberg, Germany
2 Center for Space Plasma, Aeronomy, and Astrophysics Research, University of Alabama, Huntsville, AL 35899, USA
3 Physics Department, University of Texas at Arlington, Arlington, TX 76019, USA
4 Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA

Received 17 November 1998 / Accepted 16 April 1999

Abstract

Using the Lighthill-Stein theory with modifications described by Musielak et al. (1994), the acoustic wave energy fluxes were computed for late-type stars with the solar metal abundance (population I stars) by Ulmschneider et al. (1996). We now extend these computations to stars with considerably lower metal content (population II stars with 1/10 to 1/1000 of solar metallicity) and find that the acoustic fluxes calculated for stars of different spectral types and different luminosities are affected differently by the metallicity. It is found that the Hertzsprung-Russel diagram can be subdivided into three domains (labeled I, II and III) representing a different dependence of the generated acoustic fluxes on the stellar metal abundance. For the high [FORMULA] stars of domain I there is no dependence of the generated acoustic fluxes on metallicity. In domain III are stars with low [FORMULA]. Here the generated acoustic fluxes are lowered roughly by an order of magnitude for every decrease of the metal content by an order of magnitude. Finally, domain II represents the transition between the other two domains and the generated acoustic fluxes strongly depend on [FORMULA]. The boundaries between the domains I and II, and II and III can be defined by simple relationships between stellar effective temperatures and gravities.

Key words: convection – hydrodynamics – turbulence – waves – stars: chromospheres – stars: Hertzsprung – Russel (HR) and C-M diagrams

Send offprint requests to: P. Ulmschneider

Correspondence to: ulmschneider@ita.uni-heidelberg.de

© European Southern Observatory (ESO) 1999

Online publication: June 18, 1999

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