Radio and infrared studies of mass-losing evolved stars

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5504198

Kastner, J H

Mass-losing red giant stars represent links between the late stages of stellar evolution and the chemical evolution of the galaxy. The mechanisms which lead to profuse mass loss are addressed, and the global rate of mass return to the interstellar medium (ISM) by red giants is estimated. Mass loss rates in gas, M(sub g), for 150 red giants in the solar neighborhood are estimated from a model of the circumstellar envelope and by employing a self-consistant treatment of the kinetic temperature of the gas and revised estimates of CO photodissociation radii. Analysis of the mass loss rates indicates that between 0.3 and 0.7 solar mass per year is returned to the ISM by evolved stars in the Galaxy. This is similar to an estimate of the global mass loss rate based on the white dwarf birthrate. In the solar neighborhood, roughly equal amounts are contributed by carbon-rich and oxygen-rich red giants. Comparison of M(sub g) with mass loss rates in dust shows that the dust constitutes typically approximately 1/200 of the envelope by mass. Trends in the results for mass loss rate, outflow velocity, and dust-to-gas ratio are discussed. In related studies, the results of a search for massive carbon stars in the galaxy and near-IR imaging polarimetry of the reflection nebulosity around four preplanetary nebulae are presented. In the former program, CO emission was detected for the first time from 46 evolved stars. Preliminary analysis suggests that some of the carbon stars among them are luminous, with masses of approximately 4 solar mass. In the latter study, polarization maps of CRL 2688, CRL 618, OH{sub 231}.8 + 4.2, and IRC + 10216 indicate that the imaged near-IR flux is scattered emission from embedded central sources. From a simple model, dust density gradients and total dust masses for each object are estimated.

• Research Organization: California Univ., Los Angeles, CA (United States)
• OSTI ID: 5504198
• 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 COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBON STARS
CHALCOGENIDES
COSMIC DUST
DATA
DUSTS
ELECTROMAGNETIC RADIATION
GIANT STARS
INFORMATION
INFRARED RADIATION
INFRARED SPECTRA
MAIN SEQUENCE STARS
MASS TRANSFER
MATHEMATICAL MODELS
NEAR INFRARED RADIATION
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
RADIATIONS
RED GIANT STARS
SPECTRA
STAR EVOLUTION
STAR MODELS
STARS
THEORETICAL DATA