High-pressure transition regions in stellar model chromospheres

Journal Article · Thu Nov 01 04:00:00 EST 1979 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/183091· OSTI ID:5731406

Baliunas, S L; Avrett, E H; Hartmann, L; Dupree, A K

We have investigated the implications of recent ultraviolet observations of stellar transition-region lines for calculations of the Ca II and Mg II resonance lines. We find that the adoption of high transition-region pressures for stars with active chromospheres, such as lambda And and ..cap alpha.. Aur, can be consistent with observed Ca II fluxes, contrary to the results obtained by Kelch et al. for ..cap alpha.. Aur. Furthermore, the adoption of the high-pressure models removes a long-standing difficulty in the line profile calculations, since the deep central absorption present in earlier calculations is less pronounced or absent, in closer agreement with observations. We also discuss the apparent contradiction between these models and the recent density diagnostic of Doschek et al.

• Research Organization: Harvard-Smithsonian Center for Astrophysics
• OSTI ID: 5731406
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 233:3; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
ATOMIC IONS
CALCIUM IONS
CHARGED PARTICLES
EMISSION SPECTRA
IONS
MAGNESIUM IONS
MATHEMATICAL MODELS
SPECTRA
STAR MODELS
STELLAR ATMOSPHERES
ULTRAVIOLET SPECTRA