A solar radio burst with a signal pattern, akin to that of a heartbeat, has been pinpointed in the Sun’s atmosphere. This is according to a new study from the New Jersey Institute of Technology. Here, researchers report uncovering the source location of a radio signal coming from within a C-class solar flare more than 5,000 kilometres above the Sun’s surface.
These findings could help scientists better understand the physical processes behind the energy release of solar flares. The repetitive patterns are referred to as quasi-periodic pulsations.
Solar flares are our solar system’s most powerful explosions. These are intense localized eruptions of electromagnetic radiation in the Sun’s atmosphere.
The researchers state that the discovery is unexpected. The observed beating pattern is important for understanding how energy is released and is dissipated in the Sun’s atmosphere. In addition, the researchers uncovered the source of these pattern signals after studying microwave observations of a solar flare event that occurred on July 13, 2017. The data was captured by a radio telescope called the Expanded Owens Valley Solar Array (EOVSA).
EOVSA routinely observes the Sun in a wide range of microwave frequencies over 1 to 18 gigahertz (GHz) and is sensitive to radio radiation emitted by high-energy electrons in the Sun’s atmosphere, which are energized in solar flares.
The newly captured radio bursts featured a signal pattern repeating every 10-20 seconds, “like a heartbeat,” according to the researchers. This was in the form of a strong quasi-periodic pulsation signal at the base of the electric current sheet stretching more than 25,000 kilometres through the eruption’s core flaring region.
Here, opposing magnetic field lines approach each other, break and reconnect, generating intense energy powering the flare. From this the researchers discovered a second heartbeat in the flare.
The signals likely originate from quasi-repetitive magnetic reconnections at the flare current sheet. This represents the first time a quasi-periodic radio signal located at the reconnection region has been detected. This detection can help us to determine which of the two sources caused the other one.
It was also found that the distribution of high-energy electrons in the main QPP source vary in phase with that of the secondary QPP source in the electronic current sheet.
The analysis further showed there are magnetic islands, or bubble-like structures that form in the current sheet, quasi-periodically moving toward the flaring region.
The research appears in the journal Nature Communications, titled “Microwave imaging of quasi-periodic pulsations at flare current sheet.”
