April 2, 2023

In 1999 Mysterious Finger-Like Features Were Spotted on the Sun – Now Scientists Have an Explanation

” We wished to know how these structures occur,” says lead author and CfA astronomer Chengcai Shen, who describes the structures as “dark finger-like features.” “Whats driving them and are they truly tied to magnetic reconnection?”
Researchers have actually assumed that SADs are connected to magnetic reconnection given that their discovery in the 90s. The process occurs when electromagnetic fields break, launching quickly moving and extremely energetic radiation, and then reform.
The Atmospheric Imaging Assembly (AIA) onboard NASAs Solar Dynamics Observatory catches a supra-arcade downflow within a solar flare that took place on November 29, 2020. Credit: NASA SDO/Sijie Yu
” On the Sun, what happens is you have a lot of electromagnetic fields that are pointing in all different instructions. Eventually the magnetic fields are pushed together to the point where they reconfigure and launch a great deal of energy in the type of a solar flare,” states research study co-author and CfA astronomer Kathy Reeves.
Reeves adds, “Its like extending a rubber band and snipping it in the middle. Its stressed out and extended thin, so its going to snap back.”
Scientists presumed the dark downflows were signs of the broken electromagnetic fields “snapping back” to the Sun after a solar flare eruption.
There was a catch.
Most of the downflows observed by scientists are “puzzlingly sluggish,” states co-author Bin Chen, an astronomer at the New Jersey Institute of Technology.
Shen explains, “This is not forecasted by timeless reconnection models, which reveal the downflows ought to be much quicker. Its a conflict that needs some other description.”
To discover what was happening, the team examined downflow images caught by the Atmospheric Imaging Assembly (AIA) onboard NASAs Solar Dynamics Observatory. Created and built partially at the CfA and led by the Lockheed Martin Solar Astrophysics Laboratory, the AIA takes pictures of the Sun every twelve seconds in seven different wavelengths of light to determine variations in the Suns atmosphere.
They then made 3D simulations of solar flares and compared them to the observations.
The outcomes show that most SADs are not created by magnetic reconnection. Rather, they form on their own in the turbulent environment and are the outcome of 2 fluids with different densities interacting.
Reeves says scientists are essentially seeing the exact same thing that takes place when water and oil are blended together: the 2 various fluid densities are unstable and ultimately different.
” Those dark, finger-like spaces are in fact a lack of plasma. The density is much lower there than the surrounding plasma,” Reeves states.
The group plans to continue studying SADs and other solar phenomenon using 3D simulations to much better comprehend magnetic reconnection. By comprehending the processes that drive solar flares and eruptions from the Sun, they may ultimately help establish tools to anticipate area weather condition and reduce its effects.
Referral: “The Origin of Underdense Plasma Downflows Associated with Magnetic Reconnection in Solar Flares” 27 January 2022, Nature Astronomy.DOI: 10.1038/ s41550-021-01570-2.
Extra co-authors on the paper are Xiaoyan Xie of the CfA; Sijie Yu of the New Jersey Institute of Technology; and Vanessa Polito of the Bay Area Environmental Research Institute.
This research study was supported by grants from the National Science Foundation.

Still image of numerous supra-arcade downflows, also explained as “dark, finger-like functions,” happening in a solar flare. This solar flare occurred on June 18, 2015.
In January 1999, researchers observed mysterious movements within a solar flare.
Unlike typical flares that showed bright energy emerging outwards from the Sun, this solar flare likewise showed a downward flow of motion, as if product was falling back towards the Sun. Explained as “downward-moving dark spaces,” astronomers questioned exactly what they were seeing.
Now, in a study published today (January 27, 2022) in Nature Astronomy, astronomers at the Center for Astrophysics|Harvard & & Smithsonian (CfA) use a brand-new explanation for the inadequately comprehended downflows, now referred to as supra-arcade downflows (SADs) by the clinical neighborhood.