The chromospheric structure of cool carbon stars

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5013122

Luttermoser, D G

The temperature-density structure of the outer atmospheres of the N-type carbon stars are investigated through computer generated synthetic spectra from model atmospheres. The synthetic spectra are compared to spectra obtained with the International Ultraviolet Explorer (IUE) spacecraft and ground-based photometry. The nature of the severe violet flux falloff seen in cool carbon stars is investigated through photospheric synthetic flux calculations with the assumption of local thermodynamic equilibrium (LTE). A new candidate for the unknown opacity source that causes this flux falloff is proposed-a preponderance of neutral metal bound-bound and bound-free transitions from low energy states. The chromospheric structure of these stars is also investigated through a semi-empirical modeling technique. Such a technique involves attaching a chromospheric temperature rise to a radiative equilibrium model photosphere and generating a synthetic spectrum of chromospheric spectral lines using non-LTE radiative transfer. The chromospheric temperature-density structure is then altered until the synthetic spectrum matches the IUE observations of the singly ionized magnesium resonance lines and the intercombination lines of singly ionized carbon. Through the above mentioned non-LTE analysis of the atmospheric structure of these stars, the excitation and ionization equilibria are investigated. The excited levels of H I, C I, Na I, Mg I, and Ca I are over-populated with respect to LTE in the middle and upper photosphere of these stars, and all are over-ionized with respect to LTE. Photons from the chromosphere greatly influence the excitation and ionization of H I, C I, and Mg I.

• Research Organization: Indiana Univ., Bloomington, IN (USA)
• OSTI ID: 5013122
• 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
CARBON IONS
CARBON STARS
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DENSITY
ENERGY-LEVEL TRANSITIONS
EQUILIBRIUM
EXCITATION
HYDROGEN IONS
IONIZATION
IONS
LTE
MAGNESIUM IONS
MAIN SEQUENCE STARS
MATHEMATICAL MODELS
MORPHOLOGY
OPACITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATION TRANSPORT
SIMULATION
SODIUM IONS
SPECTRA
STAR MODELS
STARS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CHROMOSPHERES
STELLAR WINDS
TEMPERATURE GRADIENTS