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Far-IR spectroscopy of the galactic center: Neutral and ionized gas in the central 10 pc of the galaxyThe 3P1 - 3P2 fine structure line emission from neutral atomic oxygen at 63 microns in the vicinity of the galactic center was mapped. The emission is extended over more than 4' (12 pc) along the galactic plane, centered on the position of Sgr A West. The line center velocities show that the O I gas is rotating around the galactic center with an axis close to that of the general galactic rotation, but there appear also to be noncircular motions. The rotational velocity at R is approximately 1 pc corresponds to a mass within the central pc of about 3 x 10(6) solar mass. Between 1 and 6 pc from the center the mass is approximately proportional to radius. The (O I) line probability arises in a predominantly neutral, atomic region immediately outside of the ionized central parsec of out galaxy. Hydrogen densities in the (O I) emitting region are 10(3) to 10(6) cm(-3) and gas temperatures are or = 100 K. The total integrated luminosity radiated in the line is about 10(5) solar luminosity, and is a substantial contribution to the cooling of the gas. Photoelectric heating or heating by ultraviolet excitation of H2 at high densities (10(5) cm(-3)) are promising mechanisms for heating of the gas, but heating due to dissipation of noncircular motions of the gas may be an alternative possibility. The 3P1 - 3P0 fine structure line of (O III) at 88 microns toward Sgr A West was also detected. The (O III) emission comes from high density ionized gas (n 10(4) cm(-3)), and there is no evidence for a medium density region (n 10(3) cm(-3)), such as the ionized halo in Sgr A West deduced from radio observations. This radio halo may be nonthermal, or may consist of many compact, dense clumps of filaments on the inner edges of neutral condensations at R or = 2 pc.
Document ID
19840015343
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Hollenbach, D. J. (California Univ. Berkeley, United States)
Watson, D. M. (California Inst. of Tech. Pasadena, United States)
Townes, C. H. (California Univ. Berkeley, United States)
Dinerstein, H. L. (Texas Univ. Austin, United States)
Hollenbach, D. (NASA Ames Research Center Moffett Field, CA, United States)
Lester, D. F. (Hawaii Univ. Honolulu, United States)
Werner, M. (NASA Ames Research Center Moffett Field, CA, United States)
Storey, J. W. V. (New South Wales Univ. Kensington, Australia)
Date Acquired
September 4, 2013
Publication Date
March 1, 1983
Subject Category
Astronomy
Report/Patent Number
NAS 1.26:166510
NASA-CR-166510
Accession Number
84N23411
Funding Number(s)
CONTRACT_GRANT: NGR-05-003-511
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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