Eta Carinae has been a source of mystery and fascination for almost two centuries. This binary star system is located some 7,500 light-years away, in the Carina constellation, and is made up of two enormous stars with 90 and 30 times the mass of our sun.
As the Inquisitr previously reported, Eta Carinae briefly became the second brightest star in the night’s sky in the 1840s, after a massive eruption that also created an hourglass-shaped gas cloud around the double star system, which became known as the Homunculus Nebula (imaged above by NASA’s Hubble Space Telescope).
A new study into the properties of Eta Carinae has revealed that this “superstar,” as NASA calls it, is even more intriguing than previously believed and actually shoots cosmic rays, some of which might even reach our planet.
These cosmic rays are “one of our few direct samples of matter from outside the solar system,” NASA explains, and pack more than one billion electron volts (eV) of energy. However, we can’t know for certain where exactly they’re coming from.
Because they’re electrically charged and they change their course under the influence of magnetic fields, the cosmic rays that reach Earth are difficult to trace back to their origins.
Yet this new study, conducted by scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and published on July 2 in the journal Nature Astronomy, proves that Eta Carinae is one of the sources that blasts cosmic rays into space and possibly sends some of them our way.
In the video below, NASA details how data from its NuSTAR space telescope uncovered that Eta Carinae, “the most luminous and massive stellar system within 10,000 light-years,” is producing cosmic rays by accelerating particles to incredibly high speeds.
“It’s more than a superstar. It’s a cosmic ray gun.”
Here’s how it all goes down.
The massive stars of Eta Carinae orbit each other once every 5.5 years, when they come “unusually close” to one another, at a distance of about 140 million miles (225 million kilometers) — or roughly the same distance between Mars and the sun.
When this happens, their stellar winds — outflows of matter coming off of the two hot stars of Eta Carinae — collide with each other, producing shock waves that accelerate particles close to the speed of light.
Some of these extremely fast particles crash into starlight, which boosts their light’s energy, turning them into X-rays and even gamma rays, reveals the new study.
“Both of Eta Carinae’s stars drive powerful outflows called stellar winds. Where these winds clash changes during the orbital cycle, which produces a periodic signal in low-energy X-rays,” explains study co-author Michael Corcoran, an astrophysicist at Goddard.
According to Corcoran, NASA has been monitoring the low-energy X-rays, or “soft” X-rays, coming from this binary star system for more than 20 years. These X-rays have been observed with both the Fermi Gamma-ray Space Telescope and NuSTAR.
The great advantage of NuSTAR is that it can zero in on high-energy X-rays as well, or “hard” X-rays, which is exactly what it did in the case of Eta Carinae. Over a period of two years, from March 2014 until June 2016, the space telescope scoured the binary star system and detected X-rays above 30,000 eV — an energy three times higher than what you’d expect from normal collisions of stellar winds.
At the same time, Fermi also identified changes in the gamma-ray emissions coming from Eta Carinae. All this points to superfast particles that evolve into cosmic rays after being accelerated by the interaction between stellar winds and colliding with starlight.
Study lead author Kenji Hamaguchi, also from Goddard, chimed in on this revelation.
“We know the blast waves of exploded stars can accelerate cosmic ray particles to speeds comparable to that of light, an incredible energy boost. Similar processes must occur in other extreme environments. Our analysis indicates Eta Carinae is one of them.”