Astronomers at the Indian Institute of Astrophysics (IIA), which operates under the Department of Science and Technology (DST), have made a significant discovery regarding the Sun’s outer layer. They have identified tiny plasma loops that could provide insights into the Sun’s hidden explosive secrets. These miniature coronal loops, which span approximately 3,000-4,000 kilometres in length but are less than 100 kilometres wide, remain elusive and have not been successfully observed until now due to their short-lived nature.
The discovery is essential as these small loops may help scientists understand how the Sun stores and releases magnetic energy. The researchers utilized advanced techniques, including high-resolution imaging and spectroscopy, to capture these fleeting structures. Annu Bura, a doctoral student at the IIA, emphasized the challenge in studying these loops, noting that they “live fast – and die young,” often lasting only a few minutes, which complicates their observation and interpretation.
The research team employed a combination of cutting-edge telescopes, including the Goode Solar Telescope at the Big Bear Solar Observatory (BBSO), NASA’s Interface Region Imaging Spectrograph (IRIS), and the Solar Dynamics Observatory (SDO). This multi-instrument approach enabled them to analyze the loops across various wavelengths, revealing their behaviour in visible light, ultraviolet, and extreme-ultraviolet regions. Using the H-alpha spectral line from hydrogen atoms, they were able to discern the loops as bright, delicate arcs located in the chromosphere, which is the layer just above the visible surface of the Sun.
Furthermore, the team applied a sophisticated technique called Differential Emission Measure analysis to determine the plasma temperature within these loops. Results indicated that the temperatures soar above several million degrees, sufficient for them to shine prominently in extreme ultraviolet wavelengths observable by the SDO’s Atmospheric Imaging Assembly.
Looking ahead, the proposed National Large Solar Telescope (NLST), set to be constructed near Pangong Lake in Ladakh, holds promise for unlocking further secrets of these small-scale solar features. This potential advancement in solar research underscores the importance of continued investment in astronomical studies, as revealed by this groundbreaking work published in The Astrophysical Journal. Through this ongoing exploration of the solar atmosphere, scientists hope to develop a deeper understanding of the complex mechanisms that govern the Sun and its impact on the solar system.
-Raja Aditya
