Ground-based detection of a vibration-rotation line of HD in Orion
arXiv:astro-ph/0201418 · doi:10.1016/S0032-0633(02)00081-8
Abstract
The v =1-0 R(5) line of HD at 2.46um has been detected at the position of brightest line emission of shocked H2 in the Orion Molecular Cloud. The flux in this HD line, when compared to that of the previously detected HD 0--0 R(5) line at 19.43um, suggests that, like the v=1 levels of H2, the v=1 levels of HD are populated in LTE, despite their much higher rates of spontaneous emission compared to H2. The higher than expected population of vibrationally excited HD may be due to chemical coupling of HD to H2 via the reactive collisions HD + H <--> H2 + D in the shocked gas. The deuterium abundance implied by the strengths of these lines relative to those of H2 is (5.1 pm 1.9 x 10^-6.
9 pages, 2 figures, Proceedings of the Conference on "Deuterium in the Universe," to be published in Planetary and Space Sciences
References in corpus (4)
- Spatial Variability in the Ratio of Interstellar Atomic Deuterium to Hydrogen. II. Observations toward Gamma2 Velorum and Zeta Puppis by the Interstellar Medium Absorption Profile Spectrograph
- ISO-SWS Observations of OMC-1: H_2 and Fine Structure Lines
- Detection of HD in the Orion molecular outflow
- Detection of a vibration-rotation emission line of hydrogen deuteride toward Orion Peak 1: excitation coupling of HD to H_2