Investigation of the late stages of stellar evolution: Mass loss from evolved stars

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

OSTI ID:6690392

Likkel, L J

In order to investigate the latest stages of stellar evolution, objects with IRAS flux densities similar to those of evolved stars with cold circumstellar material were studied. The selected objects, mostly previously unidentified, were observed for CO emission, and for H2O (22 GHz) and OH (1.6 GHz) maser emission. At least 38 of the 77 objects in the sample are evolved stars with molecular circumstellar envelopes, including 22 OH/IR stars; 22 of the evolved stars are suggested to be pre-planetary nebulae. The pre-planetary nebulae candidates in the sample fall into one or more of three groups: intermediate spectral type stars with expanding molecular shells, irregular or non-variable OH/IR stars, or oxygen-rich stars with cold circumstellar envelopes that show CO emission but not OH emission. Analysis of the OH/IR stars in the sample and similar but warmer OH/IR stars indicates that the reddest OH/IR stars have a lower scale height, and thus a larger progenitor mass, than the other OH/IR stars. The results indicate that only the reddest OH/IR stars have a scale height consistant with the previously accepted value for progenitor mass of approximately 2 to 5 solar masses and that the progenitor mass for a typical OH/IR star is approximately 1 solar mass. Three objects are discussed in detail. IRAS09371+1212, nicknamed the Frosty Leo Nebula, was identified as an evolved star by its CO profile. IRAS21282+5050 is a planetary nebula. IRAS1634-3814 was found to have an extremely unusual OH emission profile.

• Research Organization: California Univ., Los Angeles, CA (USA)
• OSTI ID: 6690392
• 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
AMPLIFIERS
ATMOSPHERES
DATA
ELECTRONIC EQUIPMENT
EQUIPMENT
EXPERIMENTAL DATA
FLUX DENSITY
HYDROGEN COMPOUNDS
INFORMATION
MASERS
MASS
MASS TRANSFER
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NEBULAE
NUMERICAL DATA
OXYGEN COMPOUNDS
PLANETARY NEBULAE
STAR EVOLUTION
STARS
STELLAR ATMOSPHERES
WATER