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

Abstract

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 processmore » after an infrared burst accompanying protostar formation.« less

Authors:
Publication Date:
Research Org.:
Division of Geological and Planetary Sciences, California Institute of Technology
OSTI Identifier:
5729532
Resource Type:
Journal Article
Journal Name:
Astrophys. J.; (United States)
Additional Journal Information:
Journal Volume: 249:1
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

Deguchi, S. Hot-gas cold-dust pumping for water masers associated with H II regions. United States: N. p., 1981. Web. doi:10.1086/159270.
Deguchi, S. Hot-gas cold-dust pumping for water masers associated with H II regions. United States. https://doi.org/10.1086/159270
Deguchi, S. 1981. "Hot-gas cold-dust pumping for water masers associated with H II regions". United States. https://doi.org/10.1086/159270.
@article{osti_5729532,
title = {Hot-gas cold-dust pumping for water masers associated with H II regions},
author = {Deguchi, S},
abstractNote = {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.},
doi = {10.1086/159270},
url = {https://www.osti.gov/biblio/5729532}, journal = {Astrophys. J.; (United States)},
number = ,
volume = 249:1,
place = {United States},
year = {Thu Oct 01 00:00:00 EDT 1981},
month = {Thu Oct 01 00:00:00 EDT 1981}
}