Further studies of vibrationally excited cyanoacetylene near Orion IRc2 and other sources

Journal Article · Sun Dec 01 04:00:00 EST 1985 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/163709· OSTI ID:6060106

Goldsmith, P F; Krotkov, R; Snell, R L

We have detected the J = 12 ..-->.. 11 transition of the v/sub 6/ = 1 vibrationally excited state of HC/sub 3/N in emission from the Orion molecular cloud. The upper level lies 750 K above the molecular ground state, and the emission can be produced only in regions of strong excitation such as the hot core; this identification is consistent with the line velocity and width. The vibrational excitation temperature of v/sub 6/ = 1 is 150 K, essentially the same as that of the v/sub 7/ = 1 and v/sub 7/ = 2 states reported previously. The extremely rapid spontaneous emission rate, 0.12 s/sup -1/, demands unreasonably high particle densities for collisions to produce the observed excitation, but is in general agreement with excitation by absorption of infrared radiation at the 20 ..mu..m wavelength of the vibrational transition. A model of the infrared excitation in the shell outside of a cavity immediately surrounding IRc2 gives satisfactory agreement with the observed intensities for reasonable choices for parameters of the exciting source and the surrounding cloud. The J = 12 ..-->.. 11 transition in the v/sub 7/ = 1 vibrationally excited cyanoacetylene which lies 354 K above the molecular ground state has been detected in three sources (in addition to Orion) among the 11 surveyed. The power emitted in the line observed is proportional to the total infrared luminosity of the source, in accord with a very simplified picture of infrared excitation.

• Research Organization: Five College Radio Astronomy Observatory; Department of Physics and Astronomy, University of Massachusetts, Amherst
• OSTI ID: 6060106
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 299:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DATA ANALYSIS
EMISSION SPECTRA
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
INTERSTELLAR GRAINS
NEBULAE
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PARTICLES
PROPIOLONITRILE
SPECTRA
VIBRATIONAL STATES