Scientists explain mysterious finger-like features in solar flares

Scientists observed motion within a solar flare in 1999.

This solar flare had a downward flow of motion as if material was falling back towards the Sun, unlike typical flares that show bright energy out from the Sun. Described as dark voids, astronomer wondered what they were seeing.

A new explanation for the poorly understood downflows is offered in a study published today in Nature Astronomy.

The structures are dark finger-like features, and lead author and CfA astronomer Chengcai Shen wants to know how they occur.

Since the discovery of magnetic reconnection, scientists have assumed that SADs are tied to it. The process occurs when the magnetic fields break.

On the Sun, there are a lot of magnetic fields that are pointing in different directions. The magnetic fields are pushed together to the point where they release a lot of energy in the form of a solar flare, according to study co-author and astronomer Kathy Reeves.

It is like stretching out a rubber band and cutting it in the middle. It is stretched thin and stressed so it will snap back.

Scientists assumed the dark downflows were signs of the broken magnetic fields after a solar flare eruption.

There was a catch.

Bin Chen is an astronomer at the New Jersey Institute of Technology.

Classic reconnection models show the downflows should be quicker. It is a conflict that requires some other explanation.

The team analyzed downflow images captured by theAIA onboard NASA's Solar Dynamics Observatory to find out what was happening. Designed and built partially at the CfA, theAIA takes images of the Sun every twelve seconds in seven different wavelength of light to measure variations in the Sun's atmosphere.

They made 3D simulations of solar flares and compared them to observations.

The results show that magnetic reconnection is not the cause of most SADs. They form on their own in the turbulent environment and are the result of two fluids interacting.

When water and oil are mixed together, the fluid densities are unstable and eventually separate.

The dark, finger-like voids are not filled with plasma. The density is lower there than in the surrounding area.

The team plans to use 3D simulations to better understand magnetic reconnection. They may help develop tools to forecast space weather and mitigate its impacts by understanding the processes that drive solar flares and eruptions from the Sun.

Xiaoyan Xie of the CfA is one of the co-authors on the paper.

More information: Chengcai Shen, The origin of underdense plasma downflows associated with magnetic reconnection in solar flares, Nature Astronomy (2022). DOI: 10.1038/s41550-021-01570-2. www.nature.com/articles/s41550-021-01570-2 Journal information: Nature Astronomy Citation: Scientists explain mysterious finger-like features in solar flares (2022, January 27) retrieved 27 January 2022 from https://phys.org/news/2022-01-scientists-mysterious-finger-like-features-solar.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.