Featured Image: Keeping Tabs on the Quiet Sun

How does the Sun’s outermost atmosphere — the solar corona — become heated to a million degrees Kelvin? The answer may lie in what’s pictured here: the quiet Sun. This extreme ultraviolet image, taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) in 2019, shows a region of the Sun spanning roughly 300 x 350 arcseconds (click for the full view). The image captures the quiet Sun — the ordinary, background roiling of the corona, unblemished by large magnetic features like active regions or coronal holes. In a new study, scientists Vishal Upendran and Durgesh Tripathi (Inter University Centre for Astronomy and Astrophysics, India) combine SDO AIA images of the quiet Sun with new models to better understand how heat may be injected into the solar corona on a continuous basis — even when the Sun is quiet. They show that impulsive events — tiny, constantly occurring nanoflares — can pump enough energy into the quiet-Sun corona to explain its mysteriously large temperature. For more information, check out the original article below.


“On the Impulsive Heating of Quiet Solar Corona,” Vishal Upendran and Durgesh Tripathi 2021 ApJ 916 59. doi:10.3847/1538-4357/abf65a