An illustration revealing EOVSA capturing a pulsating radio burst from a solar flare. Credit: Sijie Yu of NJIT/CSTR; Yuankun Kou of NJU; NASA SDO/AIA
According to a brand-new study, researchers have actually determined a solar radio burst in the Suns environment that displays a signal pattern comparable to that of a heart beat.
A global group of scientists has actually released their discovery of the source place of a radio signal emanating from a C-class solar flare over 5,000 kilometers above the surface of the Sun in the journal Nature Communications.
Scientists say the research studys findings might help researchers much better understand the physical procedures behind the energy release of solar flares– the planetary systems most effective explosions.
” The discovery is unexpected,” said Sijie Yu, the research studys corresponding author and astronomer affiliated with NJITs Center for Solar-Terrestrial Research. “This whipping pattern is essential for comprehending how energy is launched and is dissipated in the Suns environment during these incredibly effective surges on the Sun. However, the origin of these recurring patterns, likewise called quasi-periodic pulsations, has actually long been a secret and a source of argument among solar physicists.”
Solar radio bursts are extreme bursts of radio waves from the Sun, which are frequently associated with solar flares and have been understood to feature signals with duplicating patterns.
The group had the ability to reveal the source of these pattern signals after studying microwave observations of a solar flare occasion on July 13, 2017, captured by NJITs radio telescope called the Expanded Owens Valley Solar Array (EOVSA), which is located at Owens Valley Radio Observatory (OVRO), near Big Pine, Calif
. EOVSA consistently observes the Sun in a vast array of microwave frequencies over 1 to 18 gigahertz (GHz) and is sensitive to radio radiation released by high-energy electrons in the Suns environment, which are energized in solar flares.
From EOVSAs observations of the flare, the group revealed radio bursts including a signal pattern repeating every 10-20 seconds, “like a heart beat”, according to study leading author Yuankun Kou, a Ph.D. student at Nanjing University (NJU).
The team determined a strong quasi-periodic pulsation (QPP) signal at the base of the electrical current sheet stretching more than 25,000 kilometers through the eruptions core flaring region where opposing electromagnetic field lines approach each other, break and reconnect, creating extreme energy powering the flare.
Remarkably, Kou says they found a second heart beat in the flare.
” The duplicating patterns are not uncommon for solar radio bursts,” Kou stated. “But surprisingly, there is a secondary source we did not anticipate situated along the extended current sheet that pulses in a similar fashion as the main QPP source.”
” The signals likely originate from quasi-repetitive magnetic reconnections at the flare current sheet,” included Yu. “This is the very first time a quasi-periodic radio signal located at the reconnection region has actually been spotted. This detection can assist us to determine which of the 2 sources caused the other one.”
Using the distinct microwave imaging abilities of EOVSA, the group had the ability to measure the energy spectrum of electrons at the 2 radio sources in this occasion.
” EOVSAs spectral imaging gave us brand-new spatially and temporally dealt with diagnostics of the flares nonthermal electrons. … We discovered the circulation of high-energy electrons in the main QPP source vary in stage with that of the secondary QPP source in the electronic present sheet,” said Bin Chen, associate professor of physics at NJIT and co-author of the paper. “This is a strong sign that the two QPPs sources are closely associated.”
Continuing their investigation, the group members combined 2.5 D numerical modeling of the solar flare, led by the other corresponding author of the paper and professor of astronomy Xin Cheng at NJU, with observations of soft X-ray emission from the solar flares observed by NOAAs GOES satellite, which determines the soft X-ray fluxes from the Suns atmosphere in two different energy bands.
” We desired to understand how the periodicity takes place in the current sheet,” said Cheng. “What is the physical procedure driving the periodicity and how is it associated to the formation of the QPPs?”
The teams analysis revealed there are magnetic islands, or bubble-like structures that form in the existing sheet, quasi-periodically approaching the flaring area.
” The appearance of magnetic islands within the long-stretched current sheet plays an essential role in tweaking the energy release rate throughout this eruption,” described Cheng. “Such a quasi-periodic energy release procedure causes a repeating production of high-energy electrons, manifesting as QPPs in the microwave and soft X-ray wavelengths.”
Eventually, Yu says the research studys findings cast fresh light on an essential phenomenon underlying the reconnection process that drives these explosive occasions.
” Weve finally pinpointed the origin of QPPs in solar flares as an outcome of routine reconnection in the flare present sheet. … This research study triggers a reexamination of the interpretations of previously reported QPP events and their ramifications on solar flares.”
Reference: “Microwave imaging of quasi-periodic pulsations at flare current sheet” by Yuankun Kou, Xin Cheng, Yulei Wang, Sijie Yu, Bin Chen, Eduard P. Kontar and Mingde Ding, 12 December 2022, Nature Communications.DOI: 10.1038/ s41467-022-35377-0.
The research study was moneyed by the National Science Foundation.
The origin of these repetitive patterns, also called quasi-periodic pulsations, has actually long been a secret and a source of argument among solar physicists.”
” The signals likely originate from quasi-repetitive magnetic reconnections at the flare present sheet,” included Yu. “This is the first time a quasi-periodic radio signal situated at the reconnection area has actually been discovered.” EOVSAs spectral imaging gave us brand-new spatially and temporally dealt with diagnostics of the flares nonthermal electrons. … We discovered the circulation of high-energy electrons in the main QPP source differ in phase with that of the secondary QPP source in the electronic current sheet,” stated Bin Chen, associate professor of physics at NJIT and co-author of the paper.
