domingo, 28 de abril de 2013

Supernova Powered Photons --The Long-Sought 'Mystery' Source of Cosmic Rays?


Supernovae are critical to life in the universe. They and their progenitor stars create most of the elements in the universe, and their explosive deaths disburse them into interstellar space where they can later be incorporated into new stars and planets. Supernovae are also active research topics because their bright emission enables them to be used as probes of the very distant universe. Not least, supernovae are astrophysical laboratories for the study of very high-velocity shocks and the physics of particles under extreme conditions.
Harvard-Smithsonian CfA astronomer John Raymond and seven colleagues, writing in the latest issue of Science magazine, investigate the links between supernova remnants and cosmic rays - the very rapidly moving nuclear particles that impact the earth from space. Cosmic rays can have energies millions of times larger than the most energetic particles produced in man-made particle accelerators, but astronomers are not sure where they come from or how they are accelerated to such fantastic energies. Supernovae have been a likely suspect for over fifty years because their powerful shocks were thought to be capable of accelerating subatomic particles to high energies.
In their new paper, the scientists used a new optical spectrometer to analyze in detail the shock activity at the outer edge of SN1006.They report finding gas motions of over five thousand kilometers per second and evidence for the presence of fast-moving protons (as well as for fast moving but much less massive electrons).
The team suggests that such protons may be the seed particles for cosmic rays once they are further accelerated by the shocks. The study with its new techniques offer powerful new evidence towards clarifying the role of supernova remnants in the production of the mystery cosmic rays.
Journal reference: Science
Source: The Daily Galaxy via Harvard-Smithsonian Center for Astrophysics

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