Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2011-05-10
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
18 pages, 7 figures, To appear in ApJ
Scientific paper
We consider the possibility that solid molecular hydrogen is present in interstellar space. If so cosmic-rays and energetic photons cause ionisation in the solid leading to the formation of H6+. This ion is not produced by gas-phase reactions and its radiative transitions therefore provide a signature of solid H2 in the astrophysical context. The vibrational transitions of H6+ are yet to be observed in the laboratory, but we have characterised them in a quantum-theoretical treatment of the molecule; our calculations include anharmonic corrections, which are large. Here we report on those calculations and compare our results with astronomical data. In addition to the H6+ isotopomer, we focus on the deuterated species (HD)3+ which is expected to dominate at low ionisation rates as a result of isotopic condensation reactions. We can reliably predict the frequencies of the fundamental bands for five modes of vibration. For (HD)3+ all of these are found to lie close to some of the strongest of the pervasive mid-infrared astronomical emission bands, making it difficult to exclude hydrogen precipitates on observational grounds. By the same token these results suggest that (HD)3+ could be the carrier of the observed bands. We consider this possibility within the broader picture of ISM photo-processes and we conclude that solid hydrogen may indeed be abundant in astrophysical environments.
Gilbert Andrew T. B.
Lin Ching Yeh
Walker Mark A.
No associations
LandOfFree
Interstellar Solid Hydrogen does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Interstellar Solid Hydrogen, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Interstellar Solid Hydrogen will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-278828