NLTE Modeling of the Chromosphere of a Cool Giant

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Session 21 -- Stellar Spectroscopy, Atmospheres, Models, Intrinsic Variables, Theory, Part I
Display presentation, Tuesday, June 13, 1995, 9:20am - 6:30pm

[21.07] NLTE Modeling of the Chromosphere of a Cool Giant

L.Ensman, H.Johnson (Indiana U.)

In an ongoing effort to understand the chromospheres of cool evolved stars, we have attempted semi-empirical modeling of the chromospheric emission lines of the red giant $\mu$ Gem (concentrating on Mg II h and k, CII] (UV .01), and Mg I $\lambda 2852.1$). These lines have been observed at high resolution using the Hubble Space Telescope (Carpenter, etal 1995). The non-LTE models were computed using PANDORA, the atmospheres code of Avrett and Loeser, and assumed a one-component chromosphere in hydrostatic equilibrium with a simple temperature structure. 12 atomic species were included in non-LTE. Limits on the temperature and velocity structure of the chromosphere can be determined by matching the observed line profiles. The manner in which the line profiles depend on the temperature gradient in the chromosphere and it's location will be discussed; and the best model(s) for $\mu$ Gem will be presented.

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