Mysteries of Sun’s Corona Illuminated by Eclipse Data

Total Solar Eclipse

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White-light pictures of the solar corona throughout the 2019 overall solar eclipses in Chile. Credit: Solar Wind Sherpas

Researchers at the University of Hawaiʻi Institute for Astronomy (IfA) have actually been hard at work studying the solar corona, the outer environment of the sun that broadens into interplanetary area. The residential or commercial properties of the solar corona are a repercussion of the Sun’s complex electromagnetic field, which is produced in the solar interior and extends outside into area. 

IfA college student Benjamin Boe performed a brand-new research study that utilized overall solar eclipse observations to determine the shape of the coronal electromagnetic field with greater spatial resolution and over a bigger location than ever in the past. The outcomes were released in the Astrophysical Journal on June 3. 

Corona Magnetic Field

An illustration of the Sun’s corona electromagnetic field. Credit: B. Boe/UH Institute for Astronomy

The corona is most quickly seen throughout an overall solar eclipse — when the moon is straight in between the Earth and Sun, obstructing sunshine. Significant technological advances in current years have actually moved a bulk of analysis to space-based observations at wavelengths of light not available from the ground, or to big ground-based telescopes such as the Daniel K. Inouye Solar Telescope on Maui. Despite these advances, some elements of the corona can just be studied throughout overall solar eclipses. 

Boe was encouraged by UH Mānoa Astronomy Professor Shadia Habbal, a coronal research study specialist. Habbal has actually led a group of eclipse chasers, the Solar Wind Sherpas making clinical observations throughout solar eclipses for more than 20 years. These observations have actually resulted in advancements in revealing a few of the tricks of the physical procedures specifying the corona.

“The corona has been observed with total solar eclipses for well over a century, but never before had eclipse images been used to quantify its magnetic field structure,” described Boe. “I knew it would be possible to extract a lot more information by applying modern image processing techniques to solar eclipse data.” 

Solar Corona 2008 2017

High-resolution pictures of the solar corona. Top panels reveal the noticeable light (color inverted), lower panels reveal the electromagnetic field shape. Credit: B. Boe/UH Institute for Astronomy

Boe traced the pattern of the circulation of electromagnetic field lines in the corona, utilizing an automated tracing approach used to pictures of the corona taken throughout 14 eclipses the previous twenty years. This information offered the opportunity to study modifications in the corona over 2 11-year magnetic cycles of the Sun.

Boe discovered that there were really fine-scale structures throughout the corona. Higher resolution images revealed smaller-scale structures, suggesting that the corona is a lot more structured than what was formerly reported. To measure these modifications, Boe determined the electromagnetic field angle relative to the Sun’s surface area.

During durations of minimum solar activity, the corona’s field originated nearly right out of the Sun near the equator and poles, while it came out at a range of angles at mid-latitudes. During durations of optimum, the coronal electromagnetic field was far less arranged and more radial.

“We knew there would be changes over the solar cycle but we never expected how extended and structured the coronal field would be,” Boe described. “Future models will have to explain these features in order to fully understand the coronal magnetic field.”

These results obstacle the existing presumptions utilized in coronal modeling, which typically presume that the coronal electromagnetic field is radial beyond 2.5 solar radii. Instead, this work discovered that the coronal field was typically non-radial to a minimum of 4 solar radii.

This work has even more ramifications in other locations of solar research study—consisting of the development of the solar wind, which affects the Earth’s electromagnetic field and can have results on the ground, such as power interruptions.

“These results are of particular interest for solar wind formation. It indicates that the leading ideas for how to model the formation of the solar wind are not complete, and so our ability to predict and defend against space weather can be improved,” Boe stated.

Boe is currently preparing to be part of the Solar Wind Sherpas’ next eclipse explorations. The next one is slated for South America in December 2020.

Reference: “Coronal Magnetic Field Topology from Total Solar Eclipse Observations” by Benjamin Boe, Shadia Habbal and Miloslav Druckmüller, 3 June 2020, The Astrophysical Journal.
DOI: 10.3847/1538-4357/ab8ae6

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