Cosmic rays, more specifically high-speed protons, constantly bombard our Earth with potentially-harmful particles almost nonstop, but their exact origins have remained somewhat of a mystery to scientists - until now. A new study reveals that these incredibly fast-moving particles are the result of dying stars.
Supernovas, the massive explosions that result when a star dies, were found to be the source of these cosmic speed demons.
"Scientists have been trying to find the sources of high-energy cosmic rays since their discovery a century ago," said Elizabeth Hays, a member of the research team and Fermi deputy project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "Now we have conclusive proof supernova remnants, long the prime suspects, really do accelerate cosmic rays to incredible speeds."
Around 90 percent of cosmic rays are protons, with the remainder being made up of electrons and nuclei, and they can travel near the speed of light. The reason their origins were shrouded in mystery for so long to trace is that as they travel along at such speeds, magnetic field distortions cloud observations. These particles, however, can create gamma rays, which NASA's Fermi Gamma-ray Space Telescope can pick up.
"The discovery is the smoking gun that these two supernova remnants are producing accelerated protons," said lead researcher Stefan Funk, an astrophysicist with the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University in Calif. "Now we can work to better understand how they manage this feat and determine if the process is common to all remnants where we see gamma-ray emission."
You can read the full published study in the journal Science.
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