Specialized Telescope Proves a Binary Star Is a Very High-Energy Cosmic Particle Accelerator

Evidence of really high-energy gamma radiation from Eta Carinae.

With a specialized telescope in Namibia, a DESY-led group of scientists has actually shown a specific kind of binary star as a brand-new type of source for really high-energy cosmic gamma-radiation. Eta Carinae lies 7500 lightyears away in the constellation Carina (the ship’s keel) in the Southern Sky and, based upon the information gathered, discharges gamma rays with energies all the method as much as 400 gigaelectronvolts (GeV), some 100 billion times more than the energy of noticeable light. The group headed by DESY’s Stefan Ohm, Eva Leser and Matthias Füßling exists its findings, made at the gamma-ray observatory High Energy Stereoscopic System (H.E.S.S.), in the journal Astronomy & Astrophysics. A specifically developed multimedia animation discusses the phenomenon. “With such visualizations, we want to make the fascination of research tangible,” stresses DESY’s Director of Astroparticle Physics, Christian Stegmann.

Eta Carinae is a double star of superlatives, including 2 blue giants, one about 100 times, the other about 30 times the mass of our sun. The 2 stars orbit each other every 5.5 years in really eccentric elliptical orbits, their separation differing roughly in between the range from our Sun to Mars and from the Sun to Uranus. Both these enormous stars fling thick, supersonic excellent winds of charged particles out into area. In the procedure, the bigger of the 2 loses a mass equivalent to our whole Sun in simply 5000 years or two. The smaller sized one produces a quick excellent wind taking a trip at speeds around eleven million kilometers per hour (about one percent of the speed of light).

Very high-energy (VHE) gamma radiation from Eta Carinae might be found with H.E.S.S. around the time of the next encounter of the 2 huge stars. Credit: DESY, Science Communication Lab

A substantial shock front is formed in the area where these 2 excellent winds clash, warming up the product in the wind to very heats. At around 50 million degrees Celsius, this matter radiates brilliantly in the X-ray variety. The particles in the excellent wind are not hot sufficient to give off gamma radiation, however. “However, shock regions like this are typically sites where subatomic particles are accelerated by strong prevailing electromagnetic fields,” discusses Ohm, who is the head of the H.E.S.S. group at DESY. When particles are accelerated this quickly, they can likewise give off gamma radiation. In truth, the satellites “Fermi”, run by the United States area company NASA, and AGILE,  coming from the Italian area company ASI, currently found high-energy gamma rays of as much as about 10 GeV originating from Eta Carinae in 2009.

Subatomic hailstorm

“Different models have been proposed to explain how this gamma radiation is produced,” Füßling reports. “It could be generated by accelerated electrons or by high-energy atomic nuclei.” Determining which of these 2 circumstances is appropriate is important: really energetic atomic nuclei represent the bulk of the so-called Cosmic Rays, a subatomic cosmic hailstorm striking Earth continuously from all instructions. Despite extreme research study for more than 100 years, the sources of the Cosmic Rays are still not extensively understood. Since the electrically charged atomic nuclei are deflected by cosmic electromagnetic fields as they take a trip through deep space, the instructions from which they reach Earth no longer points back to their origin. Cosmic gamma rays, on the other hand, are not deflected. So, if the gamma rays given off by a particular source can be revealed to stem from high-energy atomic nuclei, among the long-sought accelerators of cosmic particle radiation will have been determined.

“In the case of Eta Carinae, electrons have a particularly hard time getting accelerated to high energies, because they are constantly being deflected by magnetic fields during their acceleration, which makes them lose energy again,” states Leser. “Very high-energy gamma radiation begins above the 100 GeV range, which is rather difficult to explain in Eta Carinae to stem from electron acceleration.” The satellite information currently suggested that Eta Carinae likewise discharges gamma radiation beyond 100 GeV, and H.E.S.S. has actually now prospered in spotting such radiation as much as energies of 400 GeV around the time of the close encounter of the 2 blue giants in 2014 and 2015. This makes the binary star the very first recognized example of a source in which really high-energy gamma radiation is produced by clashing excellent winds.

“The analysis of the gamma radiation measurements taken by H.E.S.S. and the satellites shows that the radiation can best be interpreted as the product of rapidly accelerated atomic nuclei,” states DESY’s PhD trainee Ruslan Konno, who has actually released a buddy research study, together with researchers from the Max Planck Institute for Nuclear Physics in Heidelberg. “This would make the shock regions of colliding stellar winds a new type of natural particle accelerator for cosmic rays.” With H.E.S.S., which is called after the innovator of Cosmic Rays, Victor Franz Hess, and the upcoming Cherenkov Telescope Array (CTA), the next-generation gamma-ray observatory presently being integrated in the Chilean highlands, the researchers wish to examine this phenomenon in higher information and find more sources of this kind.

Cosmic roadtrip

Thanks to in-depth observations of Eta Carinae at all wavelengths, the homes of the stars, their orbits and excellent winds have actually been figured out fairly properly. This has actually provided astrophysicists a much better image of the binary star system and its history. To highlight the brand-new observations of Eta Carinae, the DESY astrophysicists have actually produced a video animation together with the animation experts of the acclaimed Science Communication Lab. The computer-generated images are close to truth due to the fact that the determined orbital, excellent and wind criteria were utilized for this function. The globally well-known multimedia artist Carsten Nicolai, who utilizes the pseudonym Alva Noto for his musical works, developed the noise for the animation.

“I find science and scientific research extremely important,” states Nicolai, who sees close parallels in the innovative work of artists and researchers. For him, the appeal of this work likewise lay in the creative mediation of clinical research study outcomes: “particularly the fact that it is not a film soundtrack, but has a genuine reference to reality,” highlights the artist and artist. Together with the solely made up noise, this distinct partnership of researchers, animation artists, and artists has actually led to a multimedia work that takes audiences on an amazing journey to a superlative double star some 7500 light-years away.

Reference: “Detection of very-high-energy γ-ray emission from the colliding wind binary η Car with H.E.S.S.” by H.E.S.S. Collaboration, 30 March 2020, Astronomy & Astrophysics. 
DOI: 10.1051/0004-6361/201936761