High resolution J = 2 - 1 and J = 1 - 0 carbon monoxide self-reversed line profiles toward molecular clouds

Abstract

view Abstract Citations (61) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High resolution J = 2 1 and J = 1-0 carbon monoxide, self-reversed line profiles toward molecular clouds. Loren, R. B. ; Plambeck, R. L. ; Davis, J. H. ; Snell, R. L. Abstract High resolution spectra of the J =2-1 and J=1-0 transitions of 12CO and 13CO have been obtained toward eight molecular clouds which have self-reversed 12CO line profiles. Accurate comparison of these two transitions is used to infer some of the physical conditions in the cloud cores and the absorbing envelopes. The 2-1 12CO line profiles typically have deeper self-reversals but stronger line wings than the corresponding 1-0 line profiles. The CO excitation temperature of the absorbing layer is typically 10 to 18 K and no more than ∼5 K for AFGL 961. The velocity dispersion of the absorbing layer is 1.5-3.0 km s-1, about half that of the hotter cloud core. For five clouds, the velocity of this layer indicates collapse of the cloud envelope on a time scale ∼106 years. The enhancement of the 2-1 line wings compared to the 1-0 line wings indicates that this emission arises in a region with a kinetic temperature TK ≲ TPK (CO) and that the line does not become optically thin except in the extreme line wings. A greater enhancement of the low-velocity 2-1 wing indicates that a systematic collapse occurs near the cores of W3, Mon R2, ρ Oph, and Cep A. Publication: The Astrophysical Journal Pub Date: April 1981 DOI: 10.1086/158825 Bibcode: 1981ApJ...245..495L Keywords: Astronomical Spectroscopy; Carbon Monoxide; High Resolution; Interstellar Gas; Molecular Clouds; Carbon 12; Carbon 13; Line Spectra; Optical Thickness; Spectral Line Width; Astrophysics full text sources ADS | data products SIMBAD (3)