Notably, there were no linkages between this enormous explosion of energy and heightened solar activity, in fact, the sun, as per the data was quite placid at the time of the detection yet our present models of the sun can’t account for it.
An international team of almost 100 scientists was left bewildered after discovering the highest-energy light rays ever observed from the sun which has now created a new challenge for the solar physicists to solve. The finding was published in Physical Review Letters after a six-year observation by more than 30 institutions across North America, Europe, and Asia.
The discovery
The most powerful explosion of energy from the sun observed was the first ever observation of solar gamma radiation in the teraelectronvolt (TeV) region.
Scientists, since the 1990s have found that the sun releases several distinct kinds of high-energy radiation including gamma rays. However, the study published on Thursday indicated there is significantly more type of light, known as gamma rays emitted by the sun at much higher energy levels than previously believed.
“The sun is more surprising than we knew,” said Mehr Un Nisa, a postdoctoral research associate and study co-author at Michigan State University. “We thought we had this star figured out, but that’s not the case.”
Notably, there were no linkages between this enormous explosion of energy and heightened solar activity, in fact, the sun, as per the data was quite placid at the time of the detection yet our present models of the sun can’t account for it. Additionally, this form of radiation doesn’t even reach the Earth’s surface but does leave “telltale signatures”.
About the HAWC
The groundbreaking observation was taken with the High-Altitude Water Cherenkov Observatory (HAWC) which is located on the flanks of the Sierra Negra volcano near Puebla, Mexico at an altitude of roughly 13,500 feet.
What makes the site of the finding notable is that, unlike other observatories, it works around the clock. “We now have observational techniques that weren’t possible a few years ago,” added Nisa.
She noted that in this “particular energy regime” other ground-based telescopes couldn’t gaze at the sun since they only work at night, while this one operates 24/7.
HAWC uses a network of 300 big water tanks, each loaded with roughly 200 metric tonnes of water which is tucked between two dormant volcanic peaks in Mexico over 13,000 feet above sea level.
Therefore, from this “vantage point,” the researchers can examine the aftermath of gamma rays that crash with Earth’s atmosphere and by doing so form high-energy particles called air showers that are undetectable to the naked eye.
In these interactions, the gamma-ray energy is transferred into particle fragments and light which are seen by the HAWC.
What was found?
The recent analysis is based on the data collected between 2014 and 2021 and found emissions ranging between 0.5 and 2.6 TeV from the sun. Notably, among the energy at different wavelengths emitted by the sun, visible light contains energy of around 1 electron volt, compared to the 1 trillion electron volts, or 1 tera electron volt (1 TeV), that was detected by Nisa and her team.
“After looking at six years’ worth of data, out popped this excess of gamma rays,” said the study co-author. “When we first saw it, we were like, ‘We definitely messed this up. The sun cannot be this bright at these energies’,” she added.
Researchers remarked that not only was the energy level startling but so was the fact that they were seeing so much of it. Therefore, for the first time, the team has proved that the energy of the sun’s rays stretch into the TeV range, up to approximately 10 TeV, which does appear to be the maximum.