Detection of local interstellar CO absorption toward BL Lacertae

• Published in: The Astrophysical journal Vol. 371; no. 2; pp. L77 - L80
• Main Authors: MARSCHER, A. P, BANIA, T. M, ZHONG WANG
• Format: Journal Article
• Language: English
• Published: Chicago, IL University of Chicago Press 20.04.1991
• Subjects: 640102 - Astrophysics & Cosmology- Stars & Quasi-Stellar, Radio & X-Ray Sources; 640105 - Astrophysics & Cosmology- Galaxies; ABSORPTION SPECTRA; Astronomy; BL LACERTAE OBJECTS; CARBON COMPOUNDS; CARBON MONOXIDE; CARBON OXIDES; CHALCOGENIDES; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COSMIC GASES; COSMIC RADIO SOURCES; Earth, ocean, space; EMISSION SPECTRA; Exact sciences and technology; FLUIDS; GALAXIES; GASES; Interstellar medium (ism) and nebulae in milky way; INTERSTELLAR SPACE; LINE WIDTHS; MILKY WAY; Molecular clouds, h2 clouds, dense clouds, and dark clouds; OXIDES; OXYGEN COMPOUNDS; SPACE; SPECTRA; Stellar systems. Galactic and extragalactic objects and systems. The universe; High latitude; Absorption line; Extragalactic radiosource; Molecular cloud; Spectral line profile; Radio interferometric observation; Carbon monoxide; Interstellar matter; Interstellar molecule
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1086/186006

The J = O - 1 line of (C-12)O in absorption toward the compact extragalactic continuum source BL Lacertae. The absorption originates in a high-latitude molecular cloud in our Galaxy. The line is nearly black over a velocity range of 1.8 km/s, with total width comparable to that of the emission line. If the cloud is composed of many dense, optically thick clumps, with each clump absorbing over a velocity interval equal to the CO thermal velocity, it is estimated that about 70 clumps must lie along the line of sight to BL Lac in order to reproduce the characteristics of the absorption line. 16 refs.