Circumstellar shells of late-type stars - a study at millimeter and infrared wavelengths

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1985

OSTI ID:5259246

Sahai, R

An investigation (in two parts) of mass-loss envelopes around late-type stars is described concentrating on the high mass loss, carbon rich star IRC + 10216. The first part is a multi-transition study of the SiS rotational spectrum from the IRC + 10216 envelope. A numerical model to calculate the excitation of molecular rotation and vibration-rotation lines in circumstellar envelopes is developed. From fitting the observations, the author finds the (SiS)/(H/sub 2/) abundance in the inner regions of the envelope to be approx.2.4 x 10/sup -7/, roughly 100 times smaller than predicted by chemical models. The second part is an investigation of the inner (r approx. 2'') envelope of IRC + 10216, employing an annular aperture (size 2-3.45'') to measure extended emission due to resonant-scattered photons in the 4.6 ..mu..m CO vibration-rotation band. An analytical model is developed to calculate the excitation of P and R branch lines due to radiative pumping by thermal emission from dust, to fit the observations. The kinetic temperature at envelope radius r = 2'' was found to be approx.250 K, roughly twice the extrapolation of a thermodynamic model.

• Research Organization: California Inst. of Tech., Pasadena (USA)
• OSTI ID: 5259246
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
STARS
INFRARED SPECTRA
MICROWAVE RADIATION
CARBON MONOXIDE
HYDROGEN
QUANTITY RATIO
SILICON SULFIDES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
ELECTROMAGNETIC RADIATION
ELEMENTS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
SILICON COMPOUNDS
SPECTRA
SULFIDES
SULFUR COMPOUNDS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources