منابع مشابه
The galactic cosmic ray ionization rate.
The chemistry that occurs in the interstellar medium in response to cosmic ray ionization is summarized, and a review of the ionization rates that have been derived from measurements of molecular abundances is presented. The successful detection of large abundances of H(3)(+) in diffuse clouds and the recognition that dissociative recombination of H(3)(+) is fast has led to an upward revision o...
متن کاملDetermining the cosmic ray ionization rate in dynamically evolving clouds
The ionization fraction is an important factor in determining the chemical and physical evolution of star forming regions. In the dense, dark starless cores of such objects, the ionization rate is dominated by cosmic rays; it is therefore possible to use simple analytic estimators, based on the relative abundances of different molecular tracers, to determine the cosmic ray ionization rate. This...
متن کاملThe Revival of Galactic Cosmic Ray Nucleosynthesis?
Because of the roughly linear correlation between Be/H and Fe/H in low metallicity halo stars, it has been argued that a “primary” component in the nucleosynthesis of Be must be present in addition to the “secondary” component from standard Galactic cosmic ray nucleosynthesis. In this paper we critically re-evaluate the evidence for the primary versus secondary character of Li, Be, and B evolut...
متن کاملCosmic Ray Ionization of the Interstellar Medium
We consider a cosmic ray spectrum that is a power law in momentum down to a cutoff and derive a lower cutoff corresponding to Ekin ∼ (30− 60) MeV from the observed ionization rates in nearby diffuse clouds. While the real spectra of cosmic rays may not be so simple, we argue that one expects a substantial change in the spectra at such energies and that, at first approximation, a power law spect...
متن کاملModels for Galactic Cosmic-ray Propagation
A new numerical model of particle propagation in the Galaxy has been developed, which allows the study of cosmic-ray and gamma-ray production and propagation in 2D or 3D, including a full reaction network. This is a further development of the code which has been used for studies of cosmic ray reacceleration, Galactic halo size, antiprotons and positrons in cosmic rays, the interpretation of dif...
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ژورنال
عنوان ژورنال: Proceedings of the National Academy of Sciences
سال: 2006
ISSN: 0027-8424,1091-6490
DOI: 10.1073/pnas.0602117103