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Reinald Kallenbach 《Space Science Reviews》2000,92(1-2):415-419
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Bieber John W. Eroshenko Eugenia Evenson Paul Flückiger Erwin O. Kallenbach Reinald 《Space Science Reviews》2000,93(1-2):1-9
Cosmic rays provide a diagnostic tool to analyze processes in interplanetary space and at the Sun. Cosmic rays also directly
affect the terrestrial environment and serve as indicators of solar variability and non anthropogenic climatic changes on
Earth at present and in the distant past.
After the invention of the neutron monitor by John A. Simpson in 1948, an international network of cosmic ray detectors developed
in a cooperative effort to examine temporal and spatial variations in our space environment. The resulting datasets represent
the longest continuous, high time resolution series of particle radiation measurement in space science. At present, the neutron
monitor network is complemented by spacecraft instrumentation to study solar-terrestrial correlated phenomena.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Terrestrial planets are accreted in a disk orbiting a central star. The basic challenge of their formation consists of assembling
micron-sized or smaller dust grains to bodies with over 104 km in diameter. This formation process, ultimately based on collisions, occurs in three very different physical regimes depending
upon the size of the bodies present: 1) Early on, micron- to mm-sized dust grains, chondrules and chondrites are strongly
coupled to the gas. 2) As they grow larger, gravity increases the collisional cross section allowing runaway growth to occur.
3) After this runaway phase stops from exhaustion of matter in the immediate surroundings of the protoplanets, further growth
occurs on timescales typical of mutual gravitational perturbations. The emphasis of this book is on the timescales corresponding
to these formation phases as well as the characteristic chemical and isotopic composition of the bodies involved.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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The Sun is the largest reservoir of matter in the solar system, which formed 4.6 Gy ago from the protosolar nebula. The solar
wind carries a nearly unfractionated sample of heavy isotopes at energies of about 1 keV/amu from the Sun into interplanetary
space. Data from space missions and theoretical models indicate that the isotopes of the volatile elements N, O, Ne, and Ar
are fractionated by at most a few percent per atomic mass unit in different solar wind regimes. In contrast, isotopic abundances
of solar and heliospheric energetic particles at energies larger than about 100 keV/amu are observed to strongly vary relative
to solar abundances. Processes such as resonant acceleration or pre-acceleration by plasma waves, first-order Fermi acceleration,
or propagation in the interplanetary plasma are discussed as causes for charge-to-mass dependent fractionation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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