Eta Carinae shoots cosmic rays, study reports

The star system Eta Carinae is capable of launching cosmic rays across the universe.
By Joseph Scalise | Nov 12, 2018
Astronomers from NASA's Goddard Space Flight Center have used data from the NuSTAR space telescope to show that Eta Carinae -- the brightest and most massive stellar system within 10,000 light-years of Earth-- may blast out cosmic rays.

Scientists have long known that cosmic rays with energy larger than 1 billion electron volts shoot towards Earth from distant galaxies. Unfortunately, as those particles carry an electrical charge they get scrambled by the planet's magnetic field and become extremely difficult to trace.

However, Eta Carinae is a binary star system with two large stars that, as a result of their eccentric orbits, get within 140 million miles once every 5.5 years. At that time, the stellar solar winds generated by each body clash together and generate the low energy X-ray signal scientists have spent the last 20 years tracking.

In addition to those findings, the researchers also analyzed information captured by NuStar between March 2014 and June 2016 and compared it with observations taken by the European Space Agency's XMM-Newton satellite over the same period.

That revealed, besides the low energy X-rays, there were also high-energy ones generated by the shock waves in the systems colliding solar winds. In fact, some were strong enough to measure more than 30,000 electron Volts.

"We know the blast waves of exploded stars can accelerate cosmic ray particles to speeds comparable to that of light, an incredible energy boost," explained lead author Kenji Hamaguchi, an astrophysicist at NASA's Goddard Space Flight Center, according to Phys.org. "Similar processes must occur in other extreme environments. Our analysis indicates Eta Carinae is one of them."

As they are so strong, the team believes there is a good chance some of the beams move out of the star system and eventually find their way to Earth.

"We've known for some time that the region around Eta Carinae is the source of energetic emission in high-energy X-rays and gamma rays," said Fiona Harrison, a professor of astronomy at the California Institute of Technology who was not involved in the research, according to UPI. "But until NuSTAR was able to pinpoint the radiation, show it comes from the binary and study its properties in detail, the origin was mysterious."

The study is published in the journal Nature Astronomy.

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