Astronomical identification of the C/sub 3/H radical

Journal Article · Mon Jul 01 04:00:00 EDT 1985 · Astrophys. J., Lett. Ed.; (United States)

DOI:https://doi.org/10.1086/184507· OSTI ID:5403531

Thaddeus, P; Gottlieb, C A; Hjalmarson, A; Johansson, L E.B.; Irvine, W M; Friberg, P; Linke, R A

The C/sub 2/H radical, a linear carbon chain with a /sup 2/Pi electronic ground state, has been identified in the millimeter-wave spectra of two astronomical sources, IRC +10216 and TMC-1, and conclusively confirmed (accompanying Letter) in a laboratory glow discharge. In IRC +10216 four rotational transitions have been observed, three in the lower fine-structure ladder (/sup 2/Pi/sub 1/2/) and one in the upper (/sup 2/Pi/sub 3/2/), each a resolved or partially resolved lambda-doublet. In TMC-1, both lambda components of the lowest lying 1/2reverse arrow1/2 transition of the /sup 2/Pi/sub 1/2/ ladder have been observed, each with well-resolved hfs. In IRC +10216 the excitation of C/sub 3/H is similar to that of SiCC: the rotational temperature T/sub rot/ within the /sup 2/Pi/sub 1/2/ ladder is low (8.5 K), owing to rapid radiative decay, while T/sub rot/ across the ladders is high (approx.52 K) because interconnecting far-IR radiative transitions are only weakly permitted. The column density of C/sub 3/H in IRC +10216 averaged over the estimated source diameter of 84'' is 2.8 x 10/sup 13/ cm/sup -2/, an order of magnitude less than that of C/sub 2/H and C/sub 4/ H. A determination of the spectroscopic constants of C/sub 3/H that permitted the entire radio spectrum of this molecule to be calculated to high accuracy has derived from analysis of the combined astronomical and laboratory data presented in the accompanying Letter.

• Research Organization: Goddard Institute for Space Studies and Columbia University
• OSTI ID: 5403531
• Journal Information: Astrophys. J., Lett. Ed.; (United States), Journal Name: Astrophys. J., Lett. Ed.; (United States) Vol. 294:1; ISSN AJLEA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMISTRY
COSMOCHEMISTRY
DATA
ELECTROMAGNETIC RADIATION
EMISSION SPECTRA
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
INTERSTELLAR SPACE
MOLECULES
NUMERICAL DATA
ORGANIC COMPOUNDS
RADIATIONS
RADIOWAVE RADIATION
SPACE
SPECTRA
VELOCITY