Saturday noon. Only version Assigned ID: 29 ----- Submission 1 (Sat Jan 21 19:13:33 GMT 2006) ----- M supergiants have long been known to possess discrete shells of molecules, gas and most likely dust. These stars are now thought to possess quasi-static reservoirs of warm (1500K) molecules levitated above, but detached from, their photospheres, and are known as MOLspheres. This intriguing atmospheric component may be the site of material for future shell ejections or it may provide an environment in which hot, clean dust can form. Ultraviolet molecular electronic transitions are extremely sensitive diagnostics of warm circumstellar envelopes, and we propose a detailed non-LTE study of the UV signatures of CO and OH in HST spectra of the M supergiant Betelgeuse. This study will also be extended to a larger sample of stars observed with IUE. The results of this program will constrain the dynamic, thermodynamic and spatial properties of these molecules. We will test the hypothesis that the CO responsible for the observed GHRS UV absorption is part of the MOLsphere, and help complete the inventory of circumstellar molecules.

COOL STARS 12 83000.00 Univ. Colorado & GSFC with cost share false 0.0 false false false false false SUPPORTED