Hot-gas cold-dust pumping for water masers associated with H II regions

Journal Article · Thu Oct 01 00:00:00 EDT 1981 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/159270· OSTI ID:5729532

Deguchi, S

A collisional pump with an internal sink is proposed for the water masers associated with H II regions, where the population inversion occurs due to the absorption by cold ice-mantle grains in a highly dusty cloud of the far-infrared line radiation of hot water vapor. A new escape probability method is developed to calculate the transfer of line radiation in dusty medium. The pump mechanism explains the power of usual maser sources associated with H II regions and the enormous power of the sources associated with W49 N and external galaxies. Models of maser clouds have a radius of 5 x 10/sup 15/--10/sup 16/ cm, an H/sub 2/ number density of 4 x 10/sup 9/ cm/sup -3/, an expansion velocity of 10--30 km s/sup -1/, a kinetic temperature of 350 K, and a grain temperature of 100 K. Giant maser sources require grains of the size about 1 ..mu..m. The apparent size of the emission spots (approx.10/sup 13/ cm) observed by VLBI is interpreted as due to fluctuation in the cloud, and the assembly of the spots is spread within a size of 10/sup 16/ cm. The temperature difference between the dust and gas is due to a relaxation process after an infrared burst accompanying protostar formation.

• Research Organization: Division of Geological and Planetary Sciences, California Institute of Technology
• OSTI ID: 5729532
• Journal Information: Astrophys. J.; (United States), Vol. 249:1
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
H2 REGIONS
MASERS
COSMIC DUST
COSMIC GASES
ENERGY LEVELS
INTERSTELLAR GRAINS
QUANTUM MECHANICS
RADIATION TRANSPORT
AMPLIFIERS
COSMIC RADIO SOURCES
DUSTS
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUIDS
GASES
MECHANICS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
PARTICLES
640105* - Astrophysics & Cosmology- Galaxies