India's Aditya-L1 space-based solar observatory has enabled breakthrough research revealing the asymmetric expansion nature of coronal mass ejections (CMEs), with significant implications for space weather forecasting. The Visible Emission Line Coronagraph (VELC) payload, the primary instrument among Aditya-L1's seven payloads, captured spectroscopic data of a CME event on 5 August 2024 that showed distinct Doppler patterns of blueward and redward shifted emission, indicating plasma moving both toward and away from Earth simultaneously.
Researchers from the Indian Institute of Astrophysics combined VELC data with complementary observations from NASA's Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly and developed three-dimensional geometric-kinematic modeling to reconstruct the full 3D geometry and dynamics of the solar eruption. The study, published in Astrophysical Journal Letters, demonstrated for the first time that the CME did not expand outward symmetrically as previously assumed but underwent non-uniform expansion developing an asymmetric shape. The CME was launched from an active region near the western limb of the Sun and was observed using VELC's unique capability to study nascent CMEs through spectroscopy in the 530.3 nm wavelength green emission line from highly ionized iron atoms in the corona, capturing hot plasma at temperatures around 1.8 million Kelvin.
The asymmetric lateral expansion patterns observed have direct implications for how CMEs interact with solar wind and experience drag during propagation through the heliosphere, ultimately affecting their speed and arrival time at Earth. This technological advancement allows scientists to reconstruct CME motion without relying entirely on multi-viewpoint imaging from space telescopes, particularly valuable in the lower corona where CMEs evolve rapidly and their line-of-sight motion cannot be obtained from imaging alone. The VELC instrument was designed and fabricated by IIA at its MGK Menon Lab for Space Sciences on the CREST campus in Hosakote with substantial support from ISRO, and Aditya-L1 has been operational at the Sun-Earth L1 point since its September 2023 launch, providing continuous solar observations.