  We report the detection of the 1665 and 1667 MHz main lines of OH (hydroxyl)
and upper limits on the 1612 MHz satellite line of OH towards the carbon-rich
AGB star, IRC+10216. We find a beam averaged fractional abundance
x(OH)~4x10^{-8}. This detection supports the identification by Melnick et al.
(2001) of the 1_10-1_01 transition of water vapor with a 556.936 GHz emission
feature detected towards IRC+10216, since OH is the expected photodissociation
product of water vapor. The shape of the OH lines, however, differs
significantly from the shape expected based on the observations of Melnick et
al. (2001). Possible explanations for the anomalous shapes of the 1665 and 1667
MHz lines are discussed. The most likely explanations for the unexpected OH
line shapes are either masing or an asymmetric distribution of OH molecules
around IRC+10216.

Astrophysics