At about 5,000 kilometers above the Sun’s surface lies an age-old question for solar physicists: Why is the temperature in a star’s upper atmosphere (corona) hundreds of times higher than the temperature on the Sun’s visible surface? Sun?

An international team of scientists has found a new answer to the question commonly referred to as the problem of solar coronal warming, thanks to new observational data from the Goode 1.6-metre Solar Telescope (GST) at the Big Bear Solar Observatory (BBSO). It is operated by the Solar-Earth Research Center (CSTR) at NJIT.

in a published study Nature Astronomy, researchers announced that they have discovered intense wave energy from a relatively cold, dark, and highly magnetized plasma region on the Sun that can pierce the solar atmosphere and maintain temperatures of one million Kelvin within the corona. Researchers say the discovery is the final key to solving a series of related mysteries surrounding the closest star to Earth.

“The problem of heating the corona is one of the biggest mysteries in solar physics research. It’s been around for almost a century,” said Wenda Cao, BBSO director and NJIT professor of physics, who is one of the study’s co-authors. We got new answers to this problem that could be the key to solving many confusing questions.”

Using the unique imaging capabilities of the GST, the team led by Yuan Ding was first able to capture transverse oscillations in the sun’s darkest and coldest region, called the sun’s spot shadow.

Such dark regions of sunspots can occur because the star’s strong magnetic field suppresses heat conduction, preventing energy from reaching the visible surface (or photosphere) from its hotter interior, where temperatures reach around 5,000 degrees Celsius.

To investigate, the team measured the activity associated with multiple dark elements found in the active sunspot recorded by GST BBSO on July 14, 2015. 6,000 times stronger than Earth.

“Fibrils look like cone-shaped structures, typically 500-1000 km high and about 100 km wide,” explained Vasyl Yurchyshyn, professor of solar physics at NJIT-CSTR and senior scientist at BBSO. “They have a lifespan of two to three minutes, and they tend to reappear in the same place in the darkest parts of the shadow, where magnetic fields are strongest.” Source