EDITOR'S PICK
A recent study links ground and space-based observations to track structures moving through the solar corona. It was an amazing sight witnessed during theApril 2024 total solar eclipse.
For a few precious moments, it seemed like a celestial dimmer switch was thrown, as the Moon eclipsed the Sun.
It was one of the very few times you could actually see prominences and the pearly white corona of the Sun in person, without the aid of special equipment. Now, arecent studyout of the University of Hawai’i Institute for Astronomy has linked high resolution images taken during totality with observations from missions orbiting the Sun, in an effort to chronicle the evolution of space weather.
In a first, the team has demonstrated that turbulent structures forming deep in the solar corona can survive far from the Sun, as they impact space weather events stretching out across the inner solar system. The evolution of vortex rings during the 2020 and 2023 eclipses (left) versus WISPR images showing evolution in the corona.
Credit: The Astrophysical Journal/Tracking the Evolution of Plasma Instabilities from the PCTR/Creative Commons Attribution 4.0 license/DOI 10.3847. Solar prominences are seen during totality and in the hydrogen-alpha spectrum in the solar chromosphere.
Less well understood is what’s known as thesolar coronal heating mystery, and why the corona is spikes at 2 million degrees Fahrenheit, hotter than the ‘balmy’ photosphere at 10,000 degrees Fahrenheit below. Prominences tend to be radically cooler than the plasma they’re embedded within, to the tune of millions of degrees.
This steep contrast creates an instability that can trigger turbulence. Studying the corona presents a dilemma, however.
Although its about twice as bright as a Full Moon and bright enough to cast a shadow during an eclipse, it can only be seen during totality.Prominenceswere first described in the Laurentian Codex written centuries after describing theMay 1st, 1185total solar eclipse, although eclipse watchers have probably noted their presence since antiquity. The study connects deep coronal observations to activity seen farther from the Sun, in an effort to chronicle how energy is transferred.
Specifically, the study looked at the elusive prominence-corona transitioning region (PCTR) and in a first, reported on vortex rings seen emerging in PCTR.
These aren’t dissipating as expected, but instead tend to survive far from the Sun on their journey outward. "The science was triggered by the fact that plasma instabilities in general and turbulence in particular are likely to contribute to coronal heating and solar wind acceleration," lead researcher on the Study Shadia Habbal at the Institute for Astronomy told Universe Today.
"There were no observations of turbulence in the inner corona at the locus of the origination of the solar wind.
Our work is based on total solar eclipse observations in white light." "We had found in 2014 that there was a preponderance of plasma instabilities in different 'incarnations' originating from the immediate vicinity of prominences which are the coolest and most dynamic structures in the corona," says Habal.
"When PSP/WISPR reported on what they called magnetic bubbles forming in-situ, I decided to show how what they observed were nothing other than the expansion of vortex rings, Kelvin-Helmholtz instabilities and Coronal Mass Ejections (CMEs)." The study relied on several decades worth of high definition images of the Sun’s corona seen during totality.
These usedprocessing techniquespioneered by late astrophotographer M.
Druckmüller.
Dynamic captures of the solar corona farther out relied on NASA’s Parker Solar Probe WISPR (Wide-field Imager for the Parker Solar PRobe) instrument, offering an oblique view from its vantage point in heliocentric orbit of events as they stream past. "We have been acquiring total solar eclipse observations since 1995," says Habbal.
"Our observations are all taken from the ground.
At times when we were clouded out, we complemented our series of observations in white light only with images obtained by amateurs." These show the roiling vortex rings writhing and forming, like clouds in the atmosphere of Earth.