NASA’s twin Voyager explorers continue to make discoveries in interstellar space.
The Voyager mission has detected a new type of “electron burst”, which will provide insight into the mechanism of the glowing star, a new study reports.
The explosions occur when cosmic ray electrons – fast-moving particles from far beyond the solar system – are pushed by the shock waves generated by the solar eruption. The electrons then accelerated further along the lines of the cosmic magnetic field to incredible speeds, said study team members.
“The idea that shock waves accelerate particles is not new,” said author Don Gurnett, professor emeritus in physics and astronomy at the University of Iowa, in a statement. “[But] we detected it in a new realm: the interstellar medium, much different from the solar wind, where a similar process has been observed. “
The two Voyager spacecraft are still going strong after 43 years in space, with each regularly sending science back to Earth from the remaining operating instruments. (Voyager 2 flew without communication for several months in 2020 due to plans to repair and upgrade its radio communications facilities on Earth but made contact again in November.)
The first step to creating an electron explosion occurs with the release of coronal mass. This solar eruption blasts massive amounts of superheated plasma into space and creates shock waves that travel outward through the solar system.
These shock waves accelerate the fast-moving electrons of cosmic rays, charged particles likely to originate from distant supernovae. Cosmic rays are further accelerated along magnetic field lines between the stars, in the interstellar medium.
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Finally, magnetic field lines push the cosmic rays to the speed of light – nearly 670 times faster than the sun’s shock waves that first pushed them away. (The shock wave traveled at a speed of about 1 million mph, or 1.6 million kph, said study team members.)
“Physicists believe the electrons in the interstellar medium are reflected from a magnetic field amplified at the edge of the shock wave, and then accelerated by the shock wave motion,” said the University of Iowa in the same release. “The reflected electrons then rotate along the lines of the interstellar magnetic field, gaining velocity as the distance between them and the shock increases.”
Voyager 1 and Voyager 2 detected an electron burst within days of its acceleration, and later, the two probes saw an oscillation of slower-energized plasma waves through the interstellar medium generated by the electron burst.
The twin spacecraft also detected solar shock waves that originated up to a year after the event occurred; The waiting time occurs because the spacecraft is very far from the sun. Voyager 1 is about 14.1 billion miles (22.7 billion km) from the sun, and Voyager 2 is about 11.7 billion miles (18.8 billion km) from our star. (The Earth-sun average distance is approximately 93 million miles, or 150 million km.)
Astronomers hope to better understand how shock waves and cosmic radiation emanate from lit stars. Solar explosions can produce radiation that poses a risk to astronauts on the International Space Station or other destinations, such as the moon (which NASA hopes to land in 2024). An extremely powerful eruption could also threaten Earth-orbiting satellites and planetary infrastructure such as power lines.
The new study is published Wednesday (December 3) in The Astronomical Journal.
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