Formaldehyde observations in the direction of extragalactic sources

Journal Article · Wed Jan 01 04:00:00 EST 1986 · Astron. J.; (United States)

DOI:https://doi.org/10.1086/113988· OSTI ID:6449371

Colgan, S W.J.; Salpeter, E E; Terzian, Y

Absorption by galactic H/sub 2/CO has been observed with the lambda6 cm system at Arecibo towards the extragalactic sources 3C 123 and 3C 154. Towards 3C 123, which lies behind part of the Taurus cloud complex, there is both a broad and a remarkably narrow spectral component. The narrow component is at a velocity of 4.40 km s/sup -1/. It has a fitted width of only 0.12 km s/sup -1/. There is no evidence for H/sub 2/CO at a velocity of 5.5 km s/sup -1/, where other molecules have been observed. A VLA synthesis map of the H/sub 2/CO absorption has been obtained towards 3C 123. This map shows that the optical depth across 3C 123 varies less than 15% on angular scales of 3''--20''. At the estimated distance of the molecular cloud, these correspond to 0.003--0.02 pc. The velocity peak and width are constant to 0.15 km s/sup -1/ over the extent of 3C 123. Upper limits are given for H/sub 2/CO absorption towards 3C 75, 3C 138, 3C 348, 3C 390, 3C 410, and 3C 454.3.

• Research Organization: National Astronomy and Ionosphere Center, Cornell University, Ithaca, New York 14853
• OSTI ID: 6449371
• Journal Information: Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 91:1; ISSN ANJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALDEHYDES
DISTANCE
FORMALDEHYDE
INFRARED SPECTRA
INTERGALACTIC SPACE
INTERSTELLAR SPACE
ORGANIC COMPOUNDS
SPACE
SPECTRA
VELOCITY