10956(  1) - 04/03/06 11:09  - [  1]

                  HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 10956

Version: 1    Check-in Time: 03-Apr-2006 15:08:57

Title
Molecular Envelopes of M supergiants
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Type             Cycle     Parallel Pointing Tolerance
AR               15        <none>
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Investigators
                                                                                     Contact?
    PI: Dr. Graham M. Harper              University of Colorado at Boulder
   CoI: Dr. Kenneth G. Carpenter          NASA Goddard Space Flight Center              N
   CoI: Ms. Jessica E. Bartley            University of Colorado at Boulder             N

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Abstract

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.
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