It is generally believed that since the Big Bang, deuterium has only been descroyed but not created in nuclear reactions occuring inside of stars. We are analyzing Lyman resonance line absorption by interstellar deuterium and hydrogen seen in HST and FUSE spectra of nearby stars. HST and FUSE spectra covering the 912-2800 A region contain many absorption lines formed in warm clouds. We are building a three-dimensional model of the warm gas clouds within 100 pc of the Sun and developing models for the ionization balance of these clouds. See the Webpage of the Colorado Model of the Local Interstellar Cloud .
Stellar coronae are hot ionized plasmas in the outer atmospheres of most stars.
These regions are best studied using the emission lines they emit in the ultraviolet. We are analyzing HST spectra of active late-type stars and binary systems to develop models for these stars consistent with the data. The spectrum at the right shows emission lines of O VI and C II formed in the chromospheres of the G1 and G8 components of the Capella binary system. The velocity structure, mass loss rate, and ionization of the outflowing gas in late-type giants and supergiants can be inferred from high resolution spectra of optically thick lines in ultraviolet spectra and thermal radio emission. We are now developing wind models for hybrid-chromosphere stars and M supergiants.