Detection of low-J pure-rotational emission from H2 in the Orion Bar region - Evidence for small-scale clumpiness

Journal Article · Wed May 01 04:00:00 EDT 1991 · Astrophysical Journal; (United States)

DOI:https://doi.org/10.1086/186015· OSTI ID:5393123

Parmar, P S; Lacy, J H; Achtermann, J M ^[1]

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1. Texas, University, Austin (USA)

The paper presents the results of a mapping of a 10 x 16 arcsec area in the vicinity of the Orion Bar ionization front, in the v = 0 J = 3{minus}1 and J = 4{minus}2 emission lines of molecular hydrogen. This is the first detection of the J = 3{minus}1 line in the interstellar medium and the first detection of any pure-rotational H2 line in a photodissociation region. Since these lines are optically thin and thermalized, and the region is seen roughly edge-on, kinetic gas temperature and molecular column density distributions can be derived. When compared with models of photodissociation regions, the results support the scenario that the emission originates on the warm photodissociated surfaces of dense clumps of molecular gas embedded with a small volume filling factor in a low density cooler atomic medium. 23 refs.

• OSTI ID: 5393123
• Journal Information: Astrophysical Journal; (United States), Journal Name: Astrophysical Journal; (United States) Vol. 372; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPARATIVE EVALUATIONS
COSMIC GASES
COSMIC RADIO SOURCES
DETECTION
DISSOCIATION
ELEMENTS
EMISSION SPECTRA
FLUIDS
GASES
H2 REGIONS
HYDROGEN
INFRARED SPECTRA
INTERSTELLAR SPACE
MORPHOLOGY
NEBULAE
NONMETALS
QUANTUM NUMBERS
SPACE
SPECTRA