HIGH RESOLUTION OBSERVATIONS OF FAR-IR WATER LINES

this proposal requests time to extend the lws guaranteed time proposal mbarlow.hires in order to recover the original science goals. following the launch of iso, we have made the first detection from a cool star wind of the longsought rotational lines of h2o that occur in the 45181um region, in a guaranteed time lws grating spectrum of the m8e semiregular variable star w hya, an oxygenrich agb star that is a wellknown h2o and oh maser source. our modelling of the spectrum confirms that these collisionally excited thermal h2o lines are the dominant coolants in the wind, with an h2o/h2 abundance ratio of 4e4 and a mass loss rate of 6e7 msun/yr being estimated. many of the h2o lines in our lowresolution lws grating spectrum are heavily blended with other h2o lines, and the steeply rising continuum to shorter wavelengths also makes the higherexcitation lines that occur there hard to measure. this confirms our prelaunch conclusion that high resolution observations are needed to accurately determine the abundances of ortho and parah2o (which are effectively independent species), to investigate whether the h2o abundance varies as a function of radius (for which there is some evidence in our w hya grating data) and to derive the kinetic temperature profile in the wind as a function of radius. the lws consortium had allocated sufficient gt time to obtain such highresolution fabryperot (fp) observations of h2o lines from the 12 brightest oxygenrich cool stars, given prelaunch sensitivity estimates. however, with the factor of three decrease in sensitivities due to the higher than expected inorbit particle hitrate, the allocated gt time is only sufficient to obtain fp h2oline observations of 12 stars. we therefore request sufficient time to obtain such observations for a further five orich cool stars, all of them famous archetype sources. due to the unobservability of the h2o cooling lines from the ground o truncated!, Please s [truncated!, Please see actual data for full text]