Water in Betelgeuse and Antares
Donald E. Jennings,
*
Pedro V. Sada
*
Absorption lines of hot water have been identified in the infrared
spectra of Betelgeuse (
Orionis) and Antares ( Scorpii) near 12.3 micrometers (811 to 819 wavenumbers). The water lines originate in the
atmospheres of the stars, not in their circumstellar material. The
spectra are similar in structure to umbral sunspot spectra. Pure
rotation water lines of this type will occur throughout the spectra of
cool stars at wavelengths greater than 10 micrometers. From the water
spectra, the upper limit for the temperature in the line formation
region in both stars is 2800 kelvin. The water column density in both
stars is (3 ± 2) × 1018 molecules per square
centimeter, yielding an abundance relative to atomic hydrogen of
n(H2O)/n(H) 
10
7.
D. E. Jennings, Planetary Systems Branch, Code
693, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
P. V. Sada, Consultoría Astronómica de Monterrey,
Bosques de Pirineos 520-3, Col. Bosques del Valle, Garza
García, N.L. 66250, México.
*
Visiting Astronomer, National Solar Observatory, Tucson, AZ
85726, USA.
To whom correspondence should be addressed.
