Solar Orbiter Detected Small And Bright Campfires On The Sun

The ESA Solar Orbiter spacecraft is currently studying the sun. Among the discoveries made by the spacecraft so far are a surprising number of small and very bright regions in the hot solar corona that were undiscovered by other spacecraft. Tiny flares were discovered in the measurement data gathered from the Extreme-Ultraviolet Imager (EUI) taken during the commissioning of the instrument in space last year.

The team says the flares occur much more frequently than larger flares that occur on the sun. Researchers believe this could be one of the missing pieces of the puzzle they need to explain the "almost inconceivably" hot temperatures in the solar corona. The duration of these tiny flares is between 10 and 200 seconds, and they are known as solar campfires.

The temperature of the tiny campfires reaches between 1 million and 1.6 million degrees Celsius. While they are described as tiny, they are actually between 400 and 4,000 kilometers long and extend 1000 to 5000 kilometers above the sun's photosphere. The solar corona is extremely hot with a temperature of around 1 million degrees Celsius, while the photosphere has a temperature of about 5500 degrees Celsius.

Researchers have long tried to determine what causes the sun's outer atmosphere to be hotter than its surface, and that question is one of the biggest mysteries in solar physics. Researchers say computer simulations indicate reconnection drives the campfires and may generate enough energy to maintain the temperature of the corona.

The solar campfires emit an extremely short-waived ultraviolet light of high intensity for short times. In images, they appear as tiny bright spots. So far, the team has studied the properties of 1500 campfires offering the most comprehensive characterization of the phenomena ever. A study on the campfires will be published in the coming weeks.