DESY: Binary Star as a Cosmic Particle Accelerator

[bystander]

Binary Star as a Cosmic Particle Accelerator
Deutsches Elektronen-Synchrotron (DESY) | 2020 Jul 01

Specialised telescope provides evidence of very high-energy gamma radiation from Eta Carinae

In the shock region where the supersonic stellar winds of the two stars collide, subatomic particles are accelerated to such an extent that they produce very high-energy gamma radiation. Illustration: DESY, Science Communication Lab

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With a specialised telescope in Namibia a DESY-led team of researchers has proven a certain type of binary star as a new kind of source for very high-energy cosmic gamma-radiation. Eta Carinae is located 7500 lightyears away in the constellation Carina (the ship’s keel) in the Southern Sky and, based on the data collected, emits gamma rays with energies all the way up to 400 gigaelectronvolts (GeV), some 100 billion times more than the energy of visible light. ...

Eta Carinae is a binary system of superlatives, consisting of two blue giants, one about 100 times, the other about 30 times the mass of our sun. The two stars orbit each other every 5.5 years in very eccentric elliptical orbits, their separation varying approximately between the distance from our Sun to Mars and from the Sun to Uranus. Both these gigantic stars fling dense, supersonic stellar winds of charged particles out into space. In the process, the larger of the two loses a mass equivalent to our entire Sun in just 5000 years or so. The smaller one produces a fast stellar wind travelling at speeds around eleven million kilometres per hour (about one percent of the speed of light).

A huge shock front is formed in the region where these two stellar winds collide, heating up the material in the wind to extremely high temperatures. At around 50 million degrees Celsius, this matter radiates brightly in the X-ray range. The particles in the stellar wind are not hot enough to emit gamma radiation, though. “However, shock regions like this are typically sites where subatomic particles are accelerated by strong prevailing electromagnetic fields,” explains Ohm, who is the head of the H.E.S.S. group at DESY. When particles are accelerated this rapidly, they can also emit gamma radiation. In fact, the satellites “Fermi”, operated by the US space agency NASA, and AGILE, belonging to the Italian space agency ASI, already detected high-energy gamma rays of up to about 10 GeV coming from Eta Carinae in 2009. ...

Detection of Very-high-energy Gamma-ray Emission from the Colliding Wind Binary Eta Car with H.E.S.S ~ H.E.S.S. Collaboration

• Astronomy & Astrophysics 635:A137 (Mar 2020) DOI: 10.1051/0004-6361/201936761
• arXiv.org > astro-ph > arXiv:2002.02336 > 06 Feb 2020

Gamma-ray and X-ray Constraints on Non-thermal Processes in Eta Carinae ~ R. White et al

• Astronomy & Astrophysics 635:A144 (Mar 2020) DOI: 10.1051/0004-6361/201937031
• arXiv.org > astro-ph > arXiv:1911.01079 > 04 Nov 2019

[BDanielMayfield]

I highly recommend the video contained inside the article reporting this finding. It would make a most excellent APOD, as it helps to visually explain possibly the most intriguing stellar system we can see: Eta Carinae.