Molecular line studies of circumstellar envelopes

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6913931

Jewell, P R

This dissertation addresses several problems in the study of the dusty, gaseous envelopes commonly found around highly evolved stars. Most of the objects observed are M or N giants and are typically long-period variables. Some objects with hotter central stars were observed which may be young or forming planetary nebulae. Through a long-term monitoring project, properties of circumstellar ground rotational state OH masers were studied. It was found that for most sources, the variations of the OH masers at 1612, 1665, and 1667 MHz smoothly tracked the stellar variations, indicating that the masers are saturated and radiatively pumped. Extensive monitoring data were obtained on the unusual object U Orionis, which has shown non-periodic maser variations and may be in transition from one evolutionary stage to another. By carefully measuring the relative phase of variation of maser emission arising from the front and back of the circumstellar object IRC + 10011, the linear diameter of its envelope was determined. This was the first statistically significant measurement using this technique. To further investigate the excitations and pumping of circumstellar OH, a thorough search for OH masers in the two rotational states just above the ground state was undertaken. Sensitive upper limits on many sources were obtained and a new 6035 MHz OH maser in the object Vy 2-2 was detected. This source is thought to be young, compact planetary nebula. The masers may reside in the remnant of a red giant envelope.

• Research Organization: Illinois Univ., Urbana (USA)
• OSTI ID: 6913931
• 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
ABUNDANCE
AMPLIFIERS
CARBON COMPOUNDS
CARBON SULFIDES
CHALCOGENIDES
COSMIC DUST
COSMIC GASES
DUSTS
ELECTRONIC EQUIPMENT
ENERGY-LEVEL TRANSITIONS
EQUIPMENT
EXCITATION
FLUIDS
GASES
GIANT STARS
HYDROXYL RADICALS
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NEBULAE
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PLANETARY NEBULAE
PROPIOLONITRILE
RADICALS
STAR EVOLUTION
STARS
SULFIDES
SULFUR COMPOUNDS
VARIABLE STARS