What Were the Red Dots around the Total Solar Eclipse?

[Hartmann352]

Scientific American

April 8, 2024

During the total solar eclipse, skywatchers saw ruby-colored prominences sticking out of the moon's shadow. Here's the science of those red dots

BY MEGHAN BARTELS


During the total solar eclipse, skywatchers saw ruby-colored prominences sticking out of the moon's shadow. Here's the science of those red dots.

This article is part of a special report on the total solar eclipse that will be visible from parts of the U.S., Mexico and Canada on April 8, 2024.

Sky watchers got a special treat during the April 8 total solar eclipse when the always stunning spectacle of totality was adorned with a couple of solar prominences, which appeared as reddish dots in locations around the moon’s outline.

“There was a very impressive prominence visible during this eclipse,” says Lisa Upton, a solar scientist at the Southwest Research Institute in Boulder, Colo. “Stunning to behold!! This was such a magnificent eclipse for anyone who was fortunate enough to see totality.”

A total solar eclipse is the only time when earthlings can see the sun’s atmosphere, or corona. During an eclipse, the moon blocks all the light from the sun’s visible surface, which usually masks the corona. But during totality, for just a couple of minutes, the corona appears as a fiery white halo around the black moon. And scientists knew that the corona could be particularly interesting during this eclipse, which coincided neatly with the maximum of the sun’s 11-year activity cycle.

Those expectations were met when the sun provided a stunning prominence that was visible near the bottom of our host star to many during totality. (The sun’s orientation varies depending on a viewer’s location on Earth. The sun appeared to be rotated about 90 degrees between Mexico, where the eclipse’s shadow made landfall, and Canada, where it returned to the ocean.)

A solar prominence is a massive loop of the sun’s plasma that hangs attached to the visible surface of the sun, forming perhaps within a day but lasting as long as several months, according to NASA. They come in a couple of different varieties, most notably eruptive prominences, which are more dynamic structures, and quiescent ones, which can become eruptive when a new prominence forms below them.

Prominences often appear reddish because their plasma can originate deeper in the sun’s atmosphere, in a layer called the chromosphere, which is characterized by hydrogen at high temperatures that emits red light. By the 18th and 19th centuries, scientists were familiar with prominences during eclipses but initially believed that these features were potentially caused by clouds in the moon’s atmosphere. We now know that the lunar atmosphere is much too thin for clouds.

The moon does cause a different stunning phenomenon during every total solar eclipse, called Baily’s beads. These are brief flashes of light along the moon’s outline that occur at the very beginning and end of totality and are caused by sunlight sneaking through valleys on the moon’s surface. Baily’s beads aren’t visible during the rest of totality, however, like the prominences were during the April 8 eclipse.

See: https://www.scientificamerican.com/...ail&utm_term=0_b27a691814-eb308540e3-51154852

Solar prominences can vary in size and shape, ranging from small, discrete loops to large, complex structures stretching across significant portions of the solar edge and appearing red due to their predominantly Hydrogen make up.. Prominences are not technically classified as solar flares, but both appear with greater frequency during the Sun’s solar maximum phase.
Hartmann352

 

[S_Edwards]

It is interesting that most popular science websites and local news affiliates and the sort are continuing to promote the myth that the looping solar prominences are caused by magnetic field variation. Someone actually debunked this and was able to establish that these loops are optical illusions created by thermal lensing a few years back.

Thanks for sharing.

 

[Hartmann352]

I have never seen any articles on the debunking of solar prominences operating along the magnetic fields of force. Perhaps you could direct me to the appropriate article(s).

Solar prominences (or filaments) are cool dense regions of plasma that exist within the solar corona. Their existence is due to magnetic fields that support the dense plasma against gravity and insulate it from the surrounding hot coronal plasma. They can be found across all latitudes on the Sun, where their physical dimensions span a wide range of sizes (length ~60–600 Mm, height ~10–100 Mm, and width ~4–10 Mm). Their lifetime can be as long as a solar rotation (27 days), at the end of which they often erupt to initiate coronal mass ejections.


Solar filaments (aka prominences when viewed on the limb of the sun) are large, bright features extending outward from the sun’s surface. This image, from March 2010, shows a solar eruptive prominence (filament), with Earth superimposed for a sense of scale. Image via NASA.

When viewed at the highest spatial resolution, solar prominences are found to be composed of many thin co-aligned threads or vertical sheets.

Within these structures, both horizontal and vertical motions of up to 10–20 kms−1 are observed, along with a wide variety of oscillations. At the present time, a lack of detailed observations of filament formation gives rise to a wide variety of theoretical models of this process.

These models aim to explain both the formation of the prominence’s strongly sheared and highly non-potential magnetic field along with the origin of the dense plasma. Prominences also exhibit a large-scale hemispheric pattern such that “dextral” prominences containing negative magnetic helicity dominate in the northern hemisphere, while “sinistral” prominences containing positive helicity dominate in the south. Understanding this pattern is essential to understanding the build-up and release of free magnetic energy and helicity on the Sun. Future theoretical studies will have to be tightly coordinated with observations conducted at multiple wavelengths (i.e., energy levels) in order to unravel the secrets of these objects.

Researchers using NASA's Spitzer Space Telescope to study developing stars have had a hard time figuring out why the stars give off more infrared light than expected. The planet-forming disks that circle the young stars are heated by starlight and glow with infrared light, but Spitzer detected additional infrared light coming from an unknown source.

There is a new theory, based on three-dimensional models of planet-forming disks, which suggests the following: Gas and dust suspended above the pro-planetary disks are gigantic magnetic loops like those seen on the sun which absorb the starlight and glow with infrared light.

"If you could somehow stand on one of these planet-forming disks and look at the star in the center through the disk atmosphere, you would see what looks like a sunset," said Neal Turner of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The new models better describe how planet-forming material around stars is stirred up, making its way into future planets, asteroids and comets.

While the idea of magnetic atmospheres on planet-forming disks is not new, this is the first time they have been linked to the mystery of the observed excess infrared light. According to Turner and colleagues, the magnetic atmospheres are similar to what takes place on the surface of our sun, where moving magnetic field lines spur tremendous solar prominences to flare up in big loops.

Stars are born out of collapsing pockets in enormous clouds of gas and dust, rotating as they shrink down under the pull of gravity. As a star grows in size, more material rains down toward it from the cloud, and the rotation flattens this material out into a turbulent disk. Ultimately, planets clump together out of the disk material.

See: https://www.jpl.nasa.gov/news/mystery-of-planet-forming-disks-explained-by-magnetism

See: https://earthsky.org/sun/solar-filaments-prominences-arcs-hot-plasma/

Solar prominences (or filaments) are cool dense regions of plasma that exist within the solar corona. Their existence is due to magnetic fields that support the dense plasma against gravity and insulate it from the surrounding hot coronal plasma. They can be found across all latitudes on the Sun, where their physical dimensions span a wide range of sizes (length ~60–600 Mm, height ~10–100 Mm, and width ~4–10 Mm). Their lifetime can be as long as a solar rotation (27 days), at the end of which they often erupt to initiate coronal mass ejections. At the present time, a lack of detailed observations of filament formation gives rise to a wide variety of theoretical models of this process. These models aim to explain both the formation of the prominence’s strongly sheared and highly non-potential magnetic field along with the origin of the dense plasma. Prominences also exhibit a large-scale hemispheric pattern such that “dextral” prominences containing negative magnetic helicity dominate in the northern hemisphere, while “sinistral” prominences containing positive helicity dominate in the south. Understanding this pattern is essential to understanding the build-up and release of free magnetic energy and helicity on the Sun.
Hartmann352