A NASA team led by an Indian astronomer recently investigated what causes the solar corona, the outermost part of the Sun’s atmosphere, to be so hot.
At the same time, any variations in the solar corona can affect space weather and subsequently Earth activity.
So solar physicists have spent decades trying to understand the composition and behavior of the corona. Common features displayed by the solar corona include loops, streams, plumes, and outflows.
Like the green and thin algae that grow on wet rock formations near water bodies, the Sun also has algae-like patchy structures made of plasma in the solar atmosphere.
Under strong magnetic conditions, this algae grows and blooms around the center of a sunspot cluster. The moss-like structure is mainly due to ‘spicules’ interspersed with chromospheric jets or extreme UV emission components.
The algal region is connected to the lower atmosphere of the Sun and the temperature here can go up to 5.5 lakh degrees Celsius, which is 100 times higher than the immediate layer below. This long-standing mystery of more than 25 years has been partially solved by a recent NASA study.
NASA scientists used solar observations from two of its missions — the High Resolution Coronal Imager (HI-C) sounding rocket and the Interface Region Imaging Spectrograph (IRIS) — to decode the superheating mechanism.
Launched in 2013, IRIS is a small satellite-based explorer mission that routinely captures high-resolution images and spectra of the solar chromosphere and transition region. Being a sounding rocket, Hi-C is an imager designed to make short observations of the Sun’s lower coronal in the extreme ultraviolet wavelengths.
