New images of the sun reveal superfine threads of glowing plasma

The filaments are in solar regions that had appeared rather bland

close-up of the plasma filaments on the sun

A delicate comb-over of plasma filaments never seen before appears in this image (in the upper right part of the box) from NASA’s Hi-C suborbital solar telescope. The image of the full sun is from NASA’s Solar Dynamics Observatory.

University of Central Lancashire, NASA

The sharpest images yet taken of the sun’s atmosphere reveal superfine threads of hot plasma draped across small regions that have appeared rather bland until now.

Finding these slender strands is essential for understanding how energy moves around in the sun’s atmosphere, says Amy Winebarger, a solar physicist at NASA’s Marshall Space Flight Center in Huntsville, Ala. Such intel could help astronomers understand why the corona — the outer part of the sun’s atmosphere — is hundreds of times hotter than the sun’s surface (SN: 8/20/17).

Some of the newfound filaments measure just over 200 kilometers wide — they would barely fit between Washington, D.C., and Philadelphia. No one has seen them before because previous images could not resolve such fine detail in the solar corona.

UV image of plasma on the sun
Fine threads of plasma (dark lines in box) appear in this ultraviolet image of a magnetically active region on the sun from NASA’s Hi-C suborbital telescope. The entire image spans a region roughly 191,000 kilometers on a side — nearly 15 times as wide as Earth. The faint square is an artifact from the telescope.University of Central Lancashire, NASA

The pictures come courtesy of NASA’s High-Resolution Coronal Imager, or Hi-C. This small ultraviolet telescope occasionally gets hurled into space atop a rocket and then has about five minutes to snap pictures of the sun before falling back to Earth.

“We’re seeing threads pop out where we see nothing in other instruments,” says Winebarger, a coauthor of the new study, published in the April 1 Astrophysical Journal.

Hi-C spotted the solar gossamer during its second successful flight in May 2018, during which it zeroed in on a region of the sun bursting with magnetic activity. The areas laced with plasma threads in the Hi-C images appear as just a muddle of light in concurrent images from NASA’s orbiting Solar Dynamics Observatory, hinting that ever smaller structures on the sun are still waiting to be discovered.

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