Researchers from the University of Central Lancashire, working in collaboration with NASA, the Harvard-Smithsonian Center for Astrophysics and several other partners, have discovered the Sun’s major heat source. This team of researchers has captured the highest resolution images ever achieved of the Sun’s outer atmosphere (the resolution of the images is five times higher than previously obtained.)
NASA’s High Resolution Coronal Imager, also known as Hi-C, has snapped photos that offer interesting clues about a mechanism that is likely associated with the heating of the solar corona. For several decades, scientists have searched fruitlessly for something that explains why the outer parts of the solar atmosphere are on average about 400 times hotter than the surface of the Sun.
The Hi-C’s image sequences reveal the twisting up or braiding of the magnetic field that is threaded through the corona. This is a signal that energy is being added into the corona which may then be released violently, heating the electrified gases to more than two million degrees.
The space agency’s Hi-C telescope examined a large, magnetically-active region on the Sun. Some of Hi-C’s images were captured in the extreme ultraviolet part of the electromagnetic spectrum (this wavelength is the best for viewing the hot solar corona.)
Researchers believe that the new high-resolution images will help scientists increase their understanding of the mechanism behind solar flares. The images may also help scientists better predict when violent solar eruptions might take place.
“Scientists have tried for decades to understand how the solar corona is heated to millions of degrees,” said Marshall heliophysicist Dr Jonathan Cirtain, principal investigator for the Hi-C mission, in a statement. “Our team developed an exceptional instrument capable of revolutionary image resolution of the solar atmosphere. Due to the level of activity, we were able to clearly focus on an active sunspot, thereby obtaining some remarkable images.”
One physicist called this discovery a “game changer.”
“To view this magnetic braiding directly is a game changer,” said solar physicist Dr Robert Walsh, UCLan’s University Director of Research. “For the first time we can see the reconnection and unraveling of the braids within the Sun’s outer atmosphere and confirms our theory that this is one of the key processes responsible for the heating of the Sun.”
Dr. Walsh compared the magnetic braids to a rope that is seen from a great distance. From far away, the rope looks like a single object, but when one sees the rope up close, it is clear that the rope has many individual strands, braided around one another. The Hi-C’s high-resolution images allow astronomers to see the Sun’s magnetic braids up close.
The high-resolution images were made possible because of mirrors constructed at the Marshal Space Flight Center. According to researchers, the Harvard-Smithsonian Center for Astrophysics came up with a unique approach to mounting these mirrors in order to maintain the mirror resolution capability.
“This flight represents the culmination of 30 years of effort to develop these exceptionally high quality optics,” said Dr Leon Golub, Co-investigator at the Smithsonian Astrophysical Observatory.
Researchers hope that the new high-resolution images will increase their understanding of the solar atmosphere and of space weather.
“The Hi-C observations zoom in on what happens within the global view of the Sun that is seen with NASA’s Solar Dynamics Observatory. The combination of the big-picture view with the unprecedented Hi-C images shows us processes in action that we could only theorize about until now, processes that are fundamental to the workings of the solar atmosphere and all of space weather, and that apply at any other sun-like star where we would never be able to see them in action,” said Dr Karel Schrijver, SDO principal investigator and solar physicist at Lockheed Martin Solar and Astrophysics Laboratory. “The Hi-C images demonstrate that we now have the technology to make the next leap in understanding the Sun’s violent magnetism.”
The study’s findings are explained in detail in the journal Nature.
Photo credit: NASA.