This photo, based on imagery captured by the XMM-Newton and Chandra X-ray observatories, shows the supernova remnant known as RCW 86. Scientists studied the stellar leftovers to trace the source of energetic cosmic rays.

A new study shows that a supernovae will serve as gigantic particle accelerators - ranging up to almost the speed of light. This new discovery helps explain where the extremely energetic cosmic rays we find near earth come from. Cosmic rays are energetic particles originating from outer space that impinge on Earth’s atmosphere. They carry such an energetic punch they knock out electronics systems on earth if they manage to make it past our atmosphere. Almost 90% of all the incoming cosmic ray particles are protons, alomost 10% are helium nuclei (alpha particles), and slightly under 1% are heavier elements and electrons (beta minus particles). The term ray is a misnomer, as cosmic particles arrive individually, not in the form of a ray or beam of particles.

The variety of particle energies reflects the wide variety of sources. The origins of these particles range from energetic processes on the Sun all the way to as yet unknown events in the farthest reaches of the visible universe. Cosmic rays can have energies of over 1020 eV, far higher than the 1012 to 1013 eV that man-made particle accelerators can produce. There has been interest in investigating cosmic rays of even greater energies. Until now, scientist couldn’t be sure how cosmic rays acquire there energy and speed.

“It has long been thought that the super-accelerators that produce these cosmic rays in the Milky Way are the expanding envelopes created by exploded stars, but our observations reveal the smoking gun that proves it,” said Eveline Helder of the Astronomical Institute Utrecht of Utrecht University in the Netherlands, leader of the new study. The blast releases a huge amount of energy when a star dies in a supernova. Much of that energy is used to heat up a bubble of gas that expands around the remnant of the star though some energy goes toward speeding up the particles that become cosmic rays. “When a star explodes in what we call a supernova, a large part of the explosion energy is used for accelerating some particles up to extremely high energies,” Helder said. “The energy that is used for particle acceleration is at the expense of heating the gas, which is therefore much colder than theory predicts.”

Helder and team looked at the leftovers from a supernova called RCW 86 with the European Southern Observatory’s Very Large Telescope. The star exploded about 8,200 light-years away in A.D. 185, and was recorded by Chinese astronomers. The modern researchers measured the temperature and speed of the gas behind the shock wave created by the stellar explosion. They found that the gas, at 54 million degrees Fahrenheit (30 million degrees Celsius), was much lower than would be expected given the shock wave’s velocity. The astronomers concluded that rather than heat up the gas, some of the supernova’s energy went toward speeding up particles to near the velocity of light. “The missing energy is what drives the cosmic rays,” said collaborator Jacco Vink, also from the Astronomical Institute Utrecht.