Hydroxyl emission in translucent molecular clouds

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169069· OSTI ID:6405876

Magnani, L; Siskind, L ^[1]

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1. Arecibo Observatory (Puerto Rico) Minnesota Univ., Minneapolis (USA)

Observations of the 18 cm ground-state hyperfine transitions of OH in translucent molecular clouds at high Galactic latitudes are presented. Fifteen lines of sight in nine high-latitude clouds were observed with the Arecibo radio telescope. In all instances, the column density obtained from the 1665 and 1667 MHz transitions is less than 2.0 x 10 to the 14th/sq cm. If the visual extinction and gas-to-dust ratio along the observed lines of sight are typical of translucent clouds, then the OH abundance with respect to H is of order 10 to the -8th to 10 to the -7th. This value is normal for low-extinction dust clouds and contradicts an earlier study of the OH abundance in high-latitude clouds. Without an enhanced OH molecular abundance, the case for a shock-front origin for the high-latitude molecular clouds is weakened. 33 refs.

• OSTI ID: 6405876
• Journal Information: Astrophysical Journal; (USA), Vol. 359; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
HYDROXYL RADICALS
COSMOCHEMISTRY
INTERSTELLAR SPACE
CHEMICAL COMPOSITION
COSMIC DUST
COSMIC GASES
ELEMENT ABUNDANCE
HYPERFINE STRUCTURE
RADIO TELESCOPES
ABUNDANCE
ANTENNAS
CHEMISTRY
DUSTS
ELECTRICAL EQUIPMENT
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUIDS
GASES
RADICALS
RADIO EQUIPMENT
SPACE
TELESCOPES
640105* - Astrophysics & Cosmology- Galaxies