VLA observations of DR 21 NH/sub 3/ (1,1) absorption: direct evidence for clumping

Journal Article · Sun Nov 15 00:00:00 EST 1981 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/183679· OSTI ID:5567679

Matsakis, D N; Hjalmarson, A; Palmer, P; Cheung, A C; Townes, C H

The (1,1) transition of NH/sub 3/ was observed in absorption against DR 21 with a synthesized beam of 2'' size at the VLA. The DR 21 continuum is resolved by the VLA into components distributed within a range of about 30'', but only the brightest (and most southerly) component is absorbed by NH/sub 3/. The indicated filling factor and optical depth of the absorption feature are consistent with a model suggested by emission results, ammonia existing in optically thick thermalized clumps. One of these would be producing the observed absorption.

• Research Organization: U. S. Naval Observatory, Washington, D. C.
• OSTI ID: 5567679
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 250:2; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
AMMONIA
COSMIC RADIO SOURCES
DATA ANALYSIS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
H2 REGIONS
HYDRIDES
HYDROGEN COMPOUNDS
INTERFEROMETRY
INTERSTELLAR SPACE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
SPACE