Detection of the J = 2-1 transition of interstellar HC5N
Open Access
- 1 November 1978
- journal article
- research article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 185 (1) , 57P-62P
- https://doi.org/10.1093/mnras/185.1.57p
Abstract
A search made in 19 sources for the J = 2–1 transition of HC5N (at 5.3 GHz) resulted in detection in two sources only, Sgr B2 and TMC1. For Sgr B2 the J = 2–1 line transition is stronger (by approximately a factor of 5) than expected for thermal equilibrium, indicating that the transition is inverted. In TMC1 the intensity is as expected for an excitation temperature of ∼ 10 K. In both sources the ratios of the hyperfine components agree, within the error limits, with the theoretical values for LTE conditions and low optical depth. From the TMC1 observations the hyperfine splitting constant χ is estimated to be 4.275±0.015 MHz. The negative results include two sources where the detection of other transitions of HC5N has been reported. For IRC + 10216 the upper limit is compatible with the J = 9–8 line result but is lower by ∼ 50 than expected forW Hydrae.Keywords
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