Miniature Plasma Loops in Sun’s Atmosphere
Recent research by astronomers has uncovered tiny plasma loops in the lower layers of the Sun’s atmosphere. These miniature loops are extremely small and short-lived, making them difficult to detect until now. Their discovery provides new vital information about how the Sun stores and releases magnetic energy, a long-standing mystery in solar physics. The study utilised advanced telescopes and multi-wavelength observations to study these elusive structures and their dynamic behaviour.
Structure and Scale of Miniature Plasma Loops
Miniature plasma loops measure about 3,000 to 4,000 kilometres in length but are less than 100 kilometres wide. This size is roughly equivalent to the distance from Kashmir to Kanyakumari in India. These loops exist in the lower solar atmosphere, particularly in the chromosphere, a layer just above the Sun’s visible surface. Their small size and short lifespan of a few minutes made them invisible to earlier solar observations.
Observational Techniques and Instruments
The discovery was made possible by combining data from several cutting-edge instruments. The Goode Solar Telescope (GST) at the Big Bear Solar Observatory, NASA’s Interface Region Imaging Spectrograph (IRIS), and the Solar Dynamics Observatory (SDO) were used together. This multi-instrument approach enabled observations in visible, ultraviolet, and extreme-ultraviolet wavelengths, covering different layers of the Sun’s atmosphere from the chromosphere to the corona.
Physical Characteristics and Magnetic Activity
The loops appear as bright arcs in the H-alpha spectral line, a key indicator of activity in the chromosphere. Spectroscopic data revealed broadening of spectral lines and intensified signals caused by non-thermal magnetic processes. These observations suggest magnetic reconnection events, where tangled magnetic fields snap and realign, releasing bursts of energy. Plasma jets erupting from the tops of the loops are linked to these reconnection events.
Temperature and Plasma Dynamics
Using Differential Emission Measure analysis, the plasma inside these loops was found to reach temperatures of several million degrees Celsius. This is unusually hot for their location within the denser chromosphere, where such heating is difficult to explain. The loops shine brightly in extreme ultraviolet wavelengths, indicating intense energy release. Understanding this heating mechanism remains a challenge for solar physicists.
Future Prospects and Research
Future solar telescopes with higher resolution and better magnetic field sensitivity will enhance the study of these miniature loops. India’s proposed National Large Solar Telescope (NLST), a 2-metre aperture telescope planned near Pangong Lake in Ladakh, is expected to provide sharper chromospheric images. Such advancements will deepen understanding of solar magnetic processes and energy dynamics on small scales.
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