Violet and visual flux problems in red giant stars

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6062836

Faulkner, D R

Red giant stars are sites of many astrophysically interesting processes and are important links to late stages of stellar evolution and the chemical history of the galaxy. Much of what is known about stars comes from their spectra, which are formed in the outer layers (atmospheres). Unfortunately the low temperatures in red giant atmospheres promote the formation of many molecules, and the resultant complexity of the spectra has slowed progress in obtaining good models of these objects and leaves many unanswered questions. Several of these problems are investigated. Spectra of red giants provide a natural classification according to composition: M stars are oxygen rich, C stars are carbon rich, while S stars are intermediate. One long standing problem with C stars has been the explanation of the severe lack of energy flux in the violet and near ultraviolet part of their spectrum, generally attributed to an unusual opacity. Results show that one source, SiC, is untenable, while the case for the other, C3, is severely weakened. Synthetic spectra from atmospheric models are compared to spectra of TX Psc, a C star, to show that the contribution of thousands of atomic lines are probably responsible for the violet and ultraviolet flux deficiency. The agreement between the synthetic spectra and observations is very good. K and M type stars also have a violet flux deficiency, though it is less severe than with carbon stars.

• Research Organization: Indiana Univ., Bloomington, IN (USA)
• OSTI ID: 6062836
• 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
CARBON STARS
CHEMICAL COMPOSITION
DATA
ELECTROMAGNETIC RADIATION
EXPERIMENTAL DATA
FLUX DENSITY
GALACTIC EVOLUTION
GIANT STARS
INFORMATION
MAIN SEQUENCE STARS
NUMERICAL DATA
OPACITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATIONS
RED GIANT STARS
STAR EVOLUTION
STARS
ULTRAVIOLET RADIATION
VISIBLE RADIATION