Physicists report sped up electrons related to cosmic rays.
More than 40 years given that they released, the Voyager spacecraft are still making discoveries.
In a brand-new research study, a group of physicists led by the University of Iowa report the very first detection of bursts of cosmic ray electrons sped up by shock waves stemming from significant eruptions on the sun. The detection, made by instruments onboard both the Voyager 1 and Voyager 2 spacecraft, took place as the Voyagers continue their journey outside through interstellar area, hence making them the very first craft to tape-record this special physics in the world in between stars.
These recently spotted electron bursts resemble a sophisticated guard sped up along electromagnetic field lines in the interstellar medium; the electrons take a trip at almost the speed of light, some 670 times faster than the shock waves that at first moved them. The bursts were followed by plasma wave oscillations triggered by lower-energy electrons coming to the Voyagers’ instruments days later on — and lastly, in many cases, the shock wave itself as long as a month after that.
The shock waves originated from coronal mass ejections, expulsions of hot gas and energy that move outside from the sun at about one million miles per hour. Even at those speeds, it takes more than a year for the shock waves to reach the Voyager spacecraft, which have actually taken a trip even more from the sun (more than 14 billion miles and counting) than any human-made things.
“What we see here specifically is a certain mechanism whereby when the shock wave first contacts the interstellar magnetic field lines passing through the spacecraft, it reflects and accelerates some of the cosmic ray electrons,” states Don Gurnett, teacher emeritus in physics and astronomy at Iowa and the research study’s matching author. “We have identified through the cosmic ray instruments these are electrons that were reflected and accelerated by interstellar shocks propagating outward from energetic solar events at the sun. That is a new mechanism.”
The discovery might assist physicists much better comprehend the characteristics underpinning shock waves and cosmic radiation that originate from flare stars (which can differ in brightness briefly due to violent activity on their surface area) and blowing up stars. The physics of such phenomena would be very important to think about when sending out astronauts on prolonged lunar or Martian adventures, for example, throughout which they would be exposed to concentrations of cosmic rays far surpassing what we experience on Earth.
The physicists think these electrons in the interstellar medium are shown off of a strengthened electromagnetic field at the edge of the shock wave and consequently sped up by the movement of the shock wave. The showed electrons then spiral along interstellar electromagnetic field lines, getting speed as the range in between them and the shock boosts.
In a 2014 paper in the journal Astrophysical Letters, physicists J.R. Jokipii and Jozsef Kota explained in theory how ions shown from shock waves might be sped up along interstellar electromagnetic field lines. The present research study takes a look at bursts of electrons spotted by the Voyager spacecraft that are believed to be sped up by a comparable procedure.
“The idea that shock waves accelerate particles is not new,” Gurnett states. “It all has to do with how it works, the mechanism. And the fact we detected it in a new realm, the interstellar medium, which is much different than in the solar wind where similar processes have been observed. No one has seen it with an interstellar shock wave, in a whole new pristine medium.”
Reference: “A Foreshock Model for Interstellar Shocks of Solar Origin: Voyager 1 and 2 Observations” by D. A. Gurnett, W. S. Kurth, E. C. Stone, A. C. Cummings, B. Heikkila, N. Lal, S. M. Krimigis, R. B. Decker, N. F. Ness and L. F. Burlaga, 3 December 2020, The Astronomical Journal.
Co-authors consist of William Kurth from Iowa; Edward Stone and Alan Cummings from the California Institute of Technology; Bryant Heikkila, Nand Lal, and Leonard Burlaga from the NASA Goddard Space Flight Center; Stamatios Krimigis and Robert Decker from the Applied Physics Laboratory at Johns Hopkins University; and Norman Ness from the University of Delaware.
NASA moneyed the research study.