Issue |
A&A
Volume 384, Number 3, March IV 2002
|
|
---|---|---|
Page(s) | 965 - 981 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20020063 | |
Published online | 15 March 2002 |
CO 1st overtone spectra of cool evolved stars: Diagnostics for hydrodynamic atmosphere models*
Steward Observatory, The University of Arizona, Tucson AZ 85721, USA
Corresponding author: J. Bieging, jbieging@as.arizona.edu
Received:
4
October
2001
Accepted:
11
January
2002
We present spectra covering the wavelength range 2.28 to 2.36 μm at
a resolution of = 0.0007 μm (or R = 3500) for a
sample of 24 cool evolved stars. The sample comprises 8 M supergiants,
5 M giants, 3 S stars, 6 carbon stars, and 2 RV Tauri variables. The
wavelengths covered include the main parts of the 12C16O
2–0 and 3–1 overtone bands, as well as the
4–2 and 13CO
2–0 bandhead regions. CO lines dominate the spectrum for all the
stars observed, and at this resolution most of the observed features
can be identified with individual CO R- or P-branch lines or blends.
The observed transitions arise from a wide range of energy levels
extending from the ground state to
K. We looked for
correlations between the intensities of various CO absorption line
features and other stellar properties, including
IR colors and mass loss rates. Two useful CO line features
are the
2–0 R14 line, and the CO
2–0 bandhead. The intensity of
the 2–0 bandhead shows a trend with K-[12] color such that the reddest
stars (K-[12] > 3 mag) exhibit a wide range in 2–0 bandhead depth,
while the least reddened have the deepest 2–0 bandheads, with a small
range of variation from star to star. Gas mass loss rates for both
the AGB stars and the red supergiants in our sample correlate with the
K-[12] color, consistent with other studies. The data imply that stars
with
y-1 exhibit a
much narrower range in the relative strengths of CO 2–0 band features
than stars with higher mass loss rates. The range in observed spectral
properties implies that there are significant differences in
atmospheric structure among the stars in this sample.
Key words: stars: AGB and post-AGB / stars: atmospheres / stars: supergiants / infrared: stars
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.