10693(  1) - 04/05/05 12:42  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10693
                                                       Version: 1
                                                       Check-in Date: 05-Apr-2005
                                                                      16:41:52

1.Proposal Title:
Treating the UV and X-ray Spectral Regions Self-Consistently: Developing an Enhanced
Stellar Atmosphere Code
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2. Proposal For  3. Cycle  4. Parallel Pointing Tolerance
AR               14        <none>
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5. Investigators
                                                                                     Contact?
    PI: Dr. Janos Zsargo                  University of Pittsburgh
   CoI: Dr. John D. Hillier               University of Pittsburgh                      N
   CoI: Dr. Thierry Lanz                  University of Maryland                        N

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6. Abstract

We propose to implement plasma emission calculations into our widely used stellar
atmophere code (CMFGEN) to treat all relevant spectral regions, X-rays, UV, optical,
and IR self-consistently. This new version of CMFGEN will allow the stellar
community to maximize the information return from modelling efforts and utilize all
available observations simultaneously. The enhanced version will also help to
clarify the effects that X-rays have on the ionization state of the cool wind and
allow for the correct interpretation of STIS and GHRS spectra of wind-sensitive
lines. X-rays, via Auger ionization, are important in high density winds because
they produce observable quantities of super-ions, like N V and O VI. On the other
hand, preliminary results show that X-rays dominate the wind ionization balance in
OB stars with low mass-loss rates. X-ray ionization MUST be considered in such stars
if mass-loss rates and abundances are to be correctly inferred from UV wind lines.
Accurate mass-loss rates are crucial for stellar evolution calculations, while
abundances provide invaluable insights into stellar evolution.
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                                                10693(  1) - 04/05/05 12:42  - [  2]

            Summary Form for Proposal  10693

  Item                         Used in this proposal
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  Proposal Category            AR
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