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The Question

(Submitted December 19, 1996)

I am currently doing a research paper involving cosmic rays. My question is what are the effects of cosmic radiation to other stellar bodies? Or do stellar bodies affect the behavior of cosmic rays? How do cosmic particles get accelerated to speeds almost the speed of light?

The Answer

Cosmic rays generally have little effect on other stellar bodies. The energy absorbed from a cosmic ray may be re-emitted at a lower energy, but the effect is usually small.

Stellar bodies affect the trajectories of cosmic rays primarily through their magnetic fields. However, the overall magnetic field of the interstellar medium is generally more important.

The acceleration mechanism in one of the key issues in the study of cosmic rays. It is generally believed that cosmic rays are accelerated in the shocks which accompany supernova explosions. Recent evidence for this has been detected in ROSAT data of the supernova remnant SN1006. The paper describing this result appeared in the journal Nature in 1995 (the full reference is Koyama et al, Nature, 1995 vol 378, pp. 255-258). Cosmic rays may also be accelerated by the strong magnetic fields associated with pulsars.

For further discussion about cosmic rays, you might also check the book "High Energy Astrophysics" by Malcom S. Longair (2nd Edition, 1992, Cambridge). Volume 2 contains a discussion of acceleration mechanisms. You may likely find articles at more of a lay person level in back issues of Sky and Telescope or Scientific American.

I hope this is helpful.

Jim Lochner
for Imagine the Universe!

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