EAS Publications Series
Volume 60, 2013Betelgeuse Workshop 2012 The Physics of Red Supergiants: Recent Advances and Open Questions
|Page(s)||93 - 101|
|Section||Atmospheric Structure and Dynamics|
|Published online||23 May 2013|
P. Kervella, T. Le Bertre and G. Perrin (eds)
EAS Publications Series, 60 (2013) 93-101
The atmospheric structure and fundamental parameters of Red Supergiants
Dpt. Astronomia i Astrofísica, Universitat de
València, C/Dr. Moliner
2 ESO, Karl-Schwarzschild-St. 2, 85748 Garching bei München, Germany
3 Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
We present studies of the atmospheric structure and fundamental properties of the red supergiants (RSGs) VY CMa, AH Sco, UY Sct, and KW Sgr based on near-infrared K-band interferometry obtained with the VLTI/AMBER instrument with a spectral resolution of 1500. In our visibility data, we observe the presence of molecular layers of water and CO in extended atmospheres. For a uniform disk modeling, we observe size increases in the water band centered at 1.9 μm and in the CO band at 2.3–2.5 μm, with respect to the near-continuum bandpass (2.20–2.25 μm). With our spectral resolution, we obtain diameters in the near-continuum, that are free from contamination by molecular layers. Using PHOENIX atmosphere models, we estimate Rosseland-mean photospheric angular diameters of VY CMa, AH Sco, UY Sct, and KW Sgr of 11.13 ± 0.3mas, 5.81 ± 0.15mas, 5.48 ± 0.10mas, and 3.91 ± 0.25mas, respectively. We estimate radii and effective temperatures, and place the stars in the HR diagram.
The PHOENIX atmosphere models predict the spectra and the continuum visibility values, but do not predict the molecular layers visibility well: The model atmosphere is too compact when compared with the observations. This may be caused by pulsation and/or convection, which are not included in the models.
© EAS, EDP Sciences 2013