An enhanced cosmic-ray flux towards ζ Persei inferred from a laboratory study of the H3+–e- recombination rate
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- 1 April 2003
- journal article
- letter
- Published by Springer Nature in Nature
- Vol. 422 (6931) , 500-502
- https://doi.org/10.1038/nature01498
Abstract
The H3+ molecular ion plays a fundamental role in interstellar chemistry, as it initiates a network of chemical reactions that produce many molecules1,2. In dense interstellar clouds, the H3+ abundance is understood using a simple chemical model, from which observations of H3+ yield valuable estimates of cloud path length, density and temperature3,4. But observations of diffuse clouds have suggested that H3+ is considerably more abundant than expected from the chemical models5,6,7. Models of diffuse clouds have, however, been hampered by the uncertain values of three key parameters: the rate of H3+ destruction by electrons (e-), the electron fraction, and the cosmic-ray ionization rate. Here we report a direct experimental measurement of the H3+ destruction rate under nearly interstellar conditions. We also report the observation of H3+ in a diffuse cloud (towards ζ Persei) where the electron fraction is already known. From these, we find that the cosmic-ray ionization rate along this line of sight is 40 times faster than previously assumed. If such a high cosmic-ray flux is ubiquitous in diffuse clouds, the discrepancy between chemical models and the previous observations5,6,7 of H3+ can be resolved.Keywords
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This publication has 26 references indexed in Scilit:
- Observations of H3+ in the Diffuse Interstellar MediumThe Astrophysical Journal, 2002
- Dissociative recombination and excitation ofPhysical Review A, 2001
- Channel Mixing Effects in the Dissociative Recombination ofwith Slow ElectronsPhysical Review Letters, 2000
- Dissociative recombination of H 3 + : progress in theoryPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2000
- Experimental studies of the dissociative recombination of H 3 +Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2000
- Observations of H3+ in Dense Molecular CloudsThe Astrophysical Journal, 1999
- Detection of H3+ in the Diffuse Interstellar Medium: The Galactic Center and Cygnus OB2 Number 12The Astrophysical Journal, 1999
- Dissociative recombination without a curve crossingPhysical Review A, 1994
- The Formation and Depletion of Molecules in Dense Interstellar CloudsThe Astrophysical Journal, 1973
- The Rate of Formation of Interstellar Molecules by Ion-Molecule ReactionsThe Astrophysical Journal, 1973