EDP Sciences
Free access
Issue
A&A
Volume 401, Number 1, April I 2003
Page(s) 347 - 355
Section Formation and evolution of planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20030123


A&A 401, 347-355 (2003)
DOI: 10.1051/0004-6361:20030123

The structure of H $\mathsf{_{2}}$O shells in Mira atmospheres

Correlation with disk brightness distributions and a spectrophotometric signature
A. Tej1, A. Lançon1 and M. Scholz2

1  Observatoire Astronomique de Strasbourg, Université L. Pasteur & CNRS (UMR 7550), 67 000 Strasbourg, France
2  Institut f. Theoretische Astrophysik der Universität Heidelberg, Tiergartenstr. 15, 69121 Heidelberg, Germany and School of Physics, University of Sydney, NSW 2006, Australia
    e-mail: scholz@ita.uni-heidelberg.de

(Received 19 November 2002 / Accepted 6 January 2003)

Abstract
Dynamic models of M-type Mira variables predict the occurrence of water "shells", i.e. of zones of high H 2O density and high H 2O absorption inside the stellar atmosphere. The density, position and width of these shells is closely correlated with different types of two-component shapes of the intensity distribution on the disk in the H, K and L near-continuum bandpasses. We investigate these correlations and highlight the role of a spectrophotometric H 2O index that warns against serious complications in diameter measurements in the case of substantial water contamination of the bandpass of observation. Simultaneous spectrophotometric and interferometric measurements may allow observers to estimate real continuum diameters more precisely.


Key words: stars: fundamental parameters -- stars: late-type -- stars: variable: general -- stars: atmospheres

Offprint request: A. Tej, tej@astro.u-strasbg.fr

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