They discovered radio signals in a solar flare, similar to heartbeats

Space has become a constant topic in recent months. Observations, new phenomena and a science which, at the same time, never ceases to produce knowledge. Now a group of American astronomers are examining another strange signal coming from space.

This time they say the radio signals have a strange ‘heartbeat-like’ pattern and come from a source deep in the Sun’s atmosphere by detecting these clues in a C-class solar flare at over 5,000 kilometers above the surface of the Sun. .

Locating and studying solar signals could help astronomers understand the physical properties that drive solar flares, the most powerful explosions in the solar system, to unleash giant bursts of energy. The study conducted by professionals in the nanjing university in China and the New Jersey Institute of Technology in the United States it was published in the journal Nature Communications.

“The finding is unexpected,” said Sijie Yu, an astronomer at the Center for Solar-Terrestrial Research at the New Jersey Institute of Technology. This heartbeat pattern is important for understanding how energy is released and dissipated in the Sun’s atmosphere during these incredibly powerful explosions. However, the origin of these repeating patterns, also called quasi-periodic pulsations, has long been a mystery and a source of debate among solar physicists.”

Solar radio bursts are a strong release of radio waves from the Sun. Astronomers usually associate them with solar flares. When released, they emit signals in repeating patterns.

The pattern signals were located while studying microwave observations of a solar flare on July 13, 2017, using the Expanded Owns Valley Solar Array (EOVSA) telescope which looks at the Sun at a microwave frequency. wave greater than 1 to 18 gigahertz. It is sensitive to radiation emitted by high-energy electrons in the Sun’s atmosphere. High-energy electrons become especially excited when there is a solar flare.

“Observing the solar flare, the team noted radio bursts with a signal that repeated every 10 to 20 seconds. The pattern was like a heartbeat,” said Yuankun Kou, a doctoral student at the University of Nanjing in China and lead author of the study.

The team found a strong quasi-periodic pulsation (QPP) signal in the electric current extending more than 25,000 kilometers through the eruption region of the eruption core, where the opposing magnetic field lines made contact before breaking up and reconnecting. This activity accumulated energy that would be, as scientists understand, what would trigger the solar flare. The signal from one heartbeat would have been quite interesting, but the researchers soon found a second that pulsated in the same way. “It is likely that the signals come from quasi-repetitive magnetic reconnections in the flash current sheet,” Yu says. This is the first time that a quasi-periodic radio signal located in the reconnection area has been detected. This detection can help us determine which of the two sources caused the other.

Using the EOVSA telescope, the researchers measured the energy spectrum of the electrons in the two radio sources. “The EOVSA spectral images gave us new spatially and temporally resolved diagnostics of nonthermal electrons in the flare,” explained co-author Bin Chen, associate professor of physics at the New Jersey Institute of Technology. We find that the distribution of high-energy electrons in the primary QPP varies in phase with that of the secondary QPP source in the electron current sheet. This is an indication that the two sources of RRQ are closely related.”

The team also created a 2.5D digital model of the solar flare using observations from the National Oceanic and Atmospheric Administration’s GOES satellite. The satellite can measure soft X-ray emissions from the Sun’s atmosphere in two different energy bands. The results show magnetic islands or bubble-like structures forming in the current sheet and moving almost periodically through the region of the blowout.

“The appearance of magnetic islands plays a key role in adjusting the rate of energy release during this eruption,” said Xi Cheng, professor of astronomy at the New Jersey Institute of Technology. This almost periodic energy release process leads to repetitive production of high-energy electrons, which manifest as QPPs at microwave and soft X-ray wavelengths.”

According to the study authors, the findings offer new insight into what drives solar flares to occur in the first place. “This study prompts a new examination of interpretations of previously reported QPP events and their implications for solar flares,” Yu concludes.

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