AAS 200th meeting, Albuquerque, NM, June 2002
Session 74. Stellar Atmospheres and Circumstellar Material
Display, Thursday, June 6, 2002, 9:20am-4:00pm, SW Exhibit Hall

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[74.06] A Complete Linelist for the B'-X Transition of MgH

S. Skory (University of California, Berkeley), P. C. Stancil, P. F. Weck (University of Georgia), K. Kirby (Harvard-Smithsonian Center for Astrophysics)

For very cool stars (M and later), the most important source of opacity is that due to molecules. However, the lack of accurate and complete molecular data has been a serious limitation to developing atmospheric models of such stars. These models are important for producing synthetic spectra which, when compared to observations, can be used to deduce relevant physical parameters, such as surface chemical composition and effective temperature. In this work we focus on improving the molecular opacity data for the MgH molecule.

We present a comprehensive theoretical molecular linelist for the electronic transition between the B' and X states of MgH. The list contains the transition energies and oscillator strengths for all allowed rotational and vibrational transitions. The calculations use the accurate theoretical potential curves and transition dipole moment functions of Saxon et al. (1978). Using the Numerov-Cooley method, we find that there are 312 and 780 rovibrational levels in the X and B' states respectively, which give rise to a huge number of rotational transitions.

The results are compared to a linelist commonly used in stellar models, but which was obtained with questionable approximations.

This work was supported in part by the NSF REU Program at UGA and NASA grant NAG5-10551.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.