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Record Details

Record 45 of 1837
A shock origin for interstellar H2O masers
Author and Affiliation:
Hollenbach, David(NASA Ames Research Center, Moffett Field, CA, United States)
Elitzur, Moshe(Kentucky Univ., Lexington, United States)
Mckee, Christopher F.(California Univ., Berkeley, United States)
Abstract: We present a comprehensive model for the powerful H2O masers observed in starforming regions. In this model the masers occur behind dissociative shocks propagating in dense regions. This paper focuses on high-velocity dissociative shocks in which the heat of H2 reformation on dust grains maintains a large column of 300 - 400 K gas, where the chemistry drives a considerable fraction of the oxygen not in CO to form H2O. The H2O column densities, the hydrogen densities, and the warm temperatures produced by these shocks are sufficiently high to enable powerful maser action, where the maser is excited by thermal collisions with H atoms and H2 molecules. A critical ingredient in determining the shock structure is the magnetic pressure, and the fields required by our models are in agreement with recent observations. The observed brightness temperatures are the result of coherent velocity regions which have dimensions in the shock plane that are five to 50 times the postshock thickness.
Publication Date: Jan 01, 1993
Document ID:
19930068807
(Acquired Dec 28, 1995)
Accession Number: 93A52804
Subject Category: ASTROPHYSICS
Document Type: Conference Paper
Publication Information: In: Astrophysical masers; Proceedings of the Conference, Arlington, VA, Mar. 9-11, 1992 (A93-52776 23-90); p. 159-163.
Publisher Information: Springer-Verlag, Berlin and New York, Germany
Financial Sponsor: NASA; United States
Organization Source: NASA Ames Research Center; Moffett Field, CA, United States
Description: 5p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: INTERSTELLAR MASERS; STAR FORMATION; WATER MASERS; ASTRONOMICAL MODELS; BRIGHTNESS TEMPERATURE; COMPUTATIONAL ASTROPHYSICS; INTERSTELLAR MAGNETIC FIELDS; LUMINOSITY; SHOCK WAVE PROPAGATION
Imprint And Other Notes: In: Astrophysical masers; Proceedings of the Conference, Arlington, VA, Mar. 9-11, 1992 (A93-52776 23-90), p. 159-163.
Availability Source: Other Sources
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