AAS 204th Meeting, June 2004
Session 7 A Walk Through the HR Diagram
Poster, Monday, May 31, 2004, 9:20am-6:30pm, Ballroom

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[7.15] Comparison of theoretical maximum principal quantum numbers for hydrogen-like atoms in the extended atmosphere of Betelgeuse

J. E. Bartley (Boulder High Scool, Boulder, Colorado), G. M. Harper (University of Colorado)

Theoretical models predict a range of values for the maximum principal quantum number (nmax) that can exist for hydrogen-like atoms surrounded by ions, atoms and electrons. We compare the values of nmax derived from different models for conditions in the weakly ionized plasma of the extended atmosphere of the red supergiant Betelgeuse (\alpha~Ori: HD~39801). These values are used to compute optically thin free-bound and free-free sub-mm to IR continuum spectra. While there are large differences in predicted nmax from the ionized plasma, the differences in the spectra are small. This is, in part, because of the ever present free-free emission. For Betelgeuse, neutral hydrogen plays an important role in limiting (nmax). A more rigorous test of the different theoretical models would be to search for bound-bound transitions between high lying levels near nmax in plasma which is mostly ionized, e.g. H~II regions.

The work is based on research undertaken as part of Boulder Valley School District's Research Seminar in Science Program, and is co-sponsored by NSF grant AST-0206367.

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