Issue |
A&A
Volume 376, Number 1, September II 2001
|
|
---|---|---|
Page(s) | L1 - L4 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20011012 | |
Published online | 15 September 2001 |
Water in K and M giant stars unveiled by ISO*
Institute of Astronomy, The University of Tokyo, Mitaka, Tokyo 181-0015, Japan
Received:
29
May
2001
Accepted:
11
July
2001
Based on the spectra obtained with Infrared Space Observatory, ISO,
we detected the 6.3 μm bands of water in the late K giant Aldebaran
(α Tau) and several early M giant stars (between M0 and M3.5),
which have been deemed to be too warm for tri-atomic H2O molecule
to reside in their photospheres. The water column densities range
molecules cm-2 in our sample of K and M
giant stars and the excitation temperatures are 1500 K or higher. Thus,
the water bands are not originating in cool stellar winds either.
The presence of water in the K and early M giant stars was quite unexpected
from the traditional picture of the atmosphere of the red giant star
consisting of the photosphere, hot chromosphere, and cool wind. We
confirm that a rather warm molecule forming region should exist as a new
component of the atmosphere of red giant stars and that this should be
a general phenomenon in late-type stars.
Key words: infrared: stars / molecular processes / stars: atmospheres / stars: chromospheres / stars: individual: α Tau, β And, α Cet, β Peg, γ Cru / stars: late-type
© ESO, 2001
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