2006A&A...446.1119O


Query : 2006A&A...446.1119O

2006A&A...446.1119O - Astronomy and Astrophysics, volume 446, 1119-1127 (2006/2-2)

Comparison of dynamical model atmospheres of Mira variables with mid-infrared interferometric and spectroscopic observations.

OHNAKA K., SCHOLZ M. and WOOD P.R.

Abstract (from CDS):

We present a comparison of dynamical model atmospheres with mid-infrared (∼11 µm) interferometric and spectroscopic observations of the Mira variable ο Cet. The dynamical model atmospheres of Mira variables pulsating in the fundamental mode can fairly explain, without assuming ad-hoc components, the seemingly contradictory mid-infrared spectroscopic and interferometric observations of ο Cet: the 11µm sizes measured in the bandpass without any salient spectral features are about twice as large as those measured in the near-infrared. Our calculations of synthetic spectra show that the strong absorption due to a number of optically thick H2O lines is filled in by the emission of these H2O lines originating in the geometrically extended layers, providing a possible physical explanation for the picture proposed by Ohnaka (2004A&A...424.1011O) based on a semi-empirical modeling. This filling-in effect results in rather featureless, continuum-like spectra in rough agreement with the observed high-resolution 11µm spectra, although the models still predict the H2O lines to be more pronounced than the observations. The inverse P-Cyg profiles of some strong H2O lines observed in the 11µm spectra can also be reasonably reproduced by our dynamical model atmospheres. The presence of the extended H2O layers manifests itself as mid-infrared angular diameters much larger than the continuum diameter. The 11µm uniform-disk diameters predicted by our dynamical model atmospheres are in fair agreement with those observed with the Infrared Spatial Interferometer (ISI), but still somewhat smaller than the observed diameters. We discuss possible reasons for this discrepancy and problems with the current dynamical model atmospheres of Mira variables.

Abstract Copyright:

Journal keyword(s): infrared: stars - techniques: interferometric - stars: atmospheres - stars: circumstellar matter - stars: AGB and post-AGB - stars: individual: ο Cet

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 * omi Cet Mi* 02 19 20.79210 -02 58 39.4956   7.63 6.53 5.03   M5-9IIIe+DA 1528 0
2 V* IW Hya OH* 09 45 15.2390936088 -22 01 45.329402244     16     M8/9 111 0
3 V* R Leo Mi* 09 47 33.4839808805 +11 25 43.823283729 9.22 8.94 7.53 3.39 0.12 M7-9e 912 1
4 * chi Cyg S* 19 50 33.9213430345 +32 54 50.575531294 7.02 6.06 4.24 1.81 -0.01 S6-9/1-2e 694 0

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