Superstar Eta Carinae shoots cosmic rays

NASA’s NuSTAR space telescope shows that Eta Carinae, the most luminous and massive stellar system within 10,000 light-years, is accelerating cosmic rays.

more…

Tau.Neutrino said:

Superstar Eta Carinae shoots cosmic rays

NASA’s NuSTAR space telescope shows that Eta Carinae, the most luminous and massive stellar system within 10,000 light-years, is accelerating cosmic rays.

more…

Good.

Oh wait. NuSTAR doesn’t detect cosmic rays. It detects gamma rays.

> Eta Carinae, the most luminous and massive stellar system within 10,000 light-years, is accelerating particles to high energies — some of which may reach Earth as cosmic rays.

“May”. From “probabilistic words” thread, “maybe” means 55% probability. TIC.

> cosmic rays with energies greater than 1 billion electron volts (eV) come to us from beyond our solar system. But because these particles — electrons, protons and atomic nuclei — all carry an electrical charge, they veer off course whenever they encounter magnetic fields. This scrambles their paths and masks their origins.

Exactly.

> 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.

Correct.

> 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. “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 we’ve been tracking for more than two decades.NASA’s Fermi Gamma-ray Space Telescope also observes a change in gamma rays — light packing far more energy than X-rays — from a source in the direction of Eta Carinae. But Fermi’s vision isn’t as sharp as X-ray telescopes, so astronomers couldn’t confirm the connection.”

Aha. Thank you for clarification. Looking for a signal with a period of 5.5 years. How long has NuSTAR been up there? Since 2012. Just long enough to detect a 5.5 year periodicity. Nice work.

> Eta Carinae’s low-energy, or soft, X-rays come from gas at the interface of the colliding stellar winds, where temperatures exceed 70 million degrees Fahrenheit (40 million degrees Celsius). But NuSTAR detects a source emitting X-rays above 30,000 eV, some three times higher than can be explained by shock waves in the colliding winds. For comparison, the energy of visible light ranges from about 2 to 3 eV.

Bridged the gap. So now we know that Fermi’s gamma rays really do come from Eta Carinae. Am I right in thinking that the Carinae nebula is also a gamma ray source, which is what made linking Fermi’s imperfect localisation problematic? Or is it because almost all Fermi’s sources are pulsars or quasars, which makes the Eta Carinae source quite weak by comparison?

I like the way this news article is written (apart from the title).