Identification of the SiCC radical toward IRC+10216: The first molecular ring in an Astronomical source

Journal Article · Wed Aug 15 04:00:00 EDT 1984 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/184330· OSTI ID:6164208

Thaddeus, P; Cummins, S E; Linke, R A

Nine unassigned lines in the millimeter-wave spectrum of IRC+10216 have been identified as the SiCC radical, following a recent laser experiment in a supersonic molecular beam which showed that this molecule is a compact symmetric (C/sub 2//sub ..nu../) ring, not linear as previously thought. The lines attributed to SiCC are identical in shape and width as required, and their relative intensities are those expected for a prolate asymmetric top like SiCC under collisional excitation: the rotational temperature T/sub rot/ within the K-ladders is low, about 10 K, comparable to that of linear polar molecules in this source, while T/sub rot/ across the ladders is high, 140 K, because cross-ladder radiative transitions are only weakly permitted. If collisions determine the relative populations of the K-ladders, the kinetic temperture must be at least 140 K. The mean column density of SiCC over a 90'' beam derived from the rotational analysis is fairly large with respect to molecules of comparable size: 1.5 x 10/sup 14/ cm/sup -2/.

• Research Organization: Goddard Institute for Space Studies and Columbia University
• OSTI ID: 6164208
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 283:2; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CARBIDES
CARBON COMPOUNDS
CARBON STARS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
INTERSTELLAR GRAINS
MAIN SEQUENCE STARS
MOLECULAR STRUCTURE
PARTICLES
RADICALS
ROTATIONAL STATES
SILICON CARBIDES
SILICON COMPOUNDS
SPECTRA
STARS
STELLAR ATMOSPHERES