A three-year study of the OH masers in Orion-KL and a study of the (3,2) transition of ammonia

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

OSTI ID:6486259

Migenes, V

The hydroxyl masers towards Orion-KL were mapped at three epochs, January 1985, April 1986 and October 1987, by the Very Large Array (VLA). At each epoch approximately 170 OH maser features with velocities between {minus}12 to +30 km/s were found surrounding the IR sources IRc2, IRc6 and IRc7. These masers are located in an east-west distribution of 14 arc seconds in length, along a ridge defined by the NH{sub 3} emission associated with the dense hot core region. The OH masers appear to be in clumps, with diameters of approximately 0.5 to 3 inch and with dispersion velocities of 2 to 10 km/s and are probably formed in turbulent regions near the edges of shock fronts. In general the proper motions of the masers are higher than expected, but these could be interpreted as due to the turbulent motion of the material very close to young stellar objects. In addition, in January 1987, the (J,K) = (3,2) inversion line of ammonia toward Orion-KL was mapped. The VLA maps show that the emission is clumped on {approx}1 inch scales. Most of these clumps appear to be collapsing and may be protostar candidates. The width of these clumps is considerably smaller than the widths measured with single-dish radio telescopes, allowing for a qualitatively different picture of the fragmentation process on scales of 10{sup 16} cm. The OH clusters and the NH{sub 3} clumps are spatially correlated and both offer a consistent picture of the turbulent core of the Orion-KL nebula. The expanding-cylinder model for the ammonia emission can be seen as a cross section of the torus geometry delineated by masers and other molecular emission.

• Research Organization: Pennsylvania Univ., Philadelphia, PA (USA)
• OSTI ID: 6486259
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMMONIA
AMPLIFIERS
CHEMICAL COMPOSITION
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
EQUIPMENT
GRAVITATIONAL COLLAPSE
HYDRIDES
HYDROGEN COMPOUNDS
HYDROXIDES
INFRARED RADIATION
INTERSTELLAR SPACE
MAPPING
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
MORPHOLOGY
NEBULAE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
OXYGEN COMPOUNDS
PROTOSTARS
RADIATION SOURCES
RADIATIONS
RADIOWAVE RADIATION
SHOCK WAVES
SPACE
TURBULENCE
VELOCITY