Cosmic rays and gamma-rays from OB stars
Cosmic rays and gamma-rays from OB stars
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来自 OB 星的宇宙射线和伽马射线
DOI：
10.1086/159623
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
M. Forman
中科院分区：
文献类型：
--
作者：
H. Voelk;M. Forman
研究了OB星星风终端激波处宇宙线可能的加速。感兴趣的是集中在下游的相互作用区的冲击，其加速度，其传输特性。被加速的粒子可以来自星星（恒星高能粒子），也可以来自激波本身，通过恒星风等离子体的注入，来自星际介质，也可能来自激波和周围介质之间的界面。结果表明，恒星高能粒子在膨胀的风中损失了太多的能量。散射平均自由程的估计表明，激波后对流防止下游粒子进入激波，除非激波后区域由于在低密度环境介质中冷却而塌陷。不考虑电子，根据太阳风中地球弓形激波的类似结果估计，核子的激波注入将产生非相对论性核子，其动量分布近似为幂律p/sup-4/，如果它们能在激波处加速的话。这被认为是可能的，至少在恒星自转速率限制的时间尺度上是间歇性的。因此，恒星风可能是极低能量（核）宇宙射线的来源。在高环境气体密度下，这可能导致核爆炸。伽马.. -射线更高的能量。伽马.. -只有当电子能有效地注入并在冲击波处加速时，才能产生射线。«少
The possible acceleration of cosmic rays at the terminal shocks of OB star winds is investigated. Interest is focused on the interaction region downstream of the shock, its acceleration, and its transmission properties. Particles to be accelerated can come from the star (stellar energetic particles), from the shock itself through injection out of the stellar wind plasma, from the interstellar medium, and possibly from the interface between shocked wind and ambient medium. It is shown that stellar energetic particles lose far too much energy in the expanding wind to be relevant. Estimates of the scattering mean free path indicate that postshock convection prevents access of downstream particles to the shock unless the postshock region collapses due to cooling in a low density ambient medium. Disregarding electrons, shock-injection of nucleons, as estimated from analogous results at the Earth's bow shock in the solar wind, will yield nonrelativistic nucleons with a power law distribution in momentum approx.p/sup -4/ if they can be accelerated at the shock. This is believed to be possible at least intermittently on time scales limited by the stellar rotation rate. Thus, stellar winds might be sources of very low energy (nuclear) cosmic rays. At high ambient gas densitiesmore » this may lead to nuclear ..gamma..-rays. Higher energy ..gamma..-rays could be produced only by electrons if they can be efficiently injected and accelerated at the shock.« less