JPL News: NuSTAR Mission Proves Superstar Eta Carinae Shoots Cosmic Rays

A new study using data from the NuSTAR space telescope suggests that Eta Carinae, the most luminous and massive stellar system within 10,000 light-years of Earth, is accelerating particles to high energies—some of which may reach our planet as cosmic rays.  

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

Eta Carinae, located about 7,500 light-years away in the southern constellation of Carina, is famous for a 19th century outburst that briefly made it the second-brightest star in the sky. This event also ejected a massive hourglass-shaped nebula, but the cause of the eruption remains poorly understood.

The system contains a pair of massive stars whose eccentric orbits bring them unusually close every 5.5 years. The stars contain 90 and 30 times the mass of our sun and pass 140 million miles (225 million kilometers) apart at their closest approach—about the average distance separating Mars and the sun.

"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," says Fiona Harrison, the principal investigator of NuSTAR; the Benjamin M. Rosen Professor of Physics; and the Kent and Joyce Kresa Leadership Chair of the division of physics, mathematics and astronomy at Caltech. "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."

Read the full story at JPL News. 

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR's mission operations center is at UC Berkeley, and the official data archive is at NASA's High Energy Astrophysics Science Archive Research Center. ASI provides the mission's ground station and a mirror archive. Caltech manages JPL for NASA.