Aditya-L1 VELC Finds Solar Eruption Expands Asymmetrically

Data from the Visible Emission Line Coronagraph (VELC) aboard Aditya-L1, India's first space-based solar observatory, has shown for the first time that a solar eruption does not swell outward from the Sun as a neat symmetric bubble. Instead the eruption expands unevenly and takes on an asymmetric shape. The Ministry of Science and Technology announced the finding on 3 November 2026.

The spacecraft and its payload

Aditya-L1 was launched in September 2023 and now works from the Sun-Earth L1 point, from where it watches the Sun without a break. It carries 7 payloads, and VELC is the primary one. VELC is an internally occulted coronagraph, an instrument that blocks the bright solar disk so that the far fainter corona around it can be studied, and it can observe the corona in several modes at once.

What the study found

Scientists of the Indian Institute of Astrophysics (IIA), an autonomous institution of the Department of Science and Technology, combined VELC data with observations from the Atmospheric Imaging Assembly on NASA's Solar Dynamics Observatory (SDO) and with three-dimensional modelling to rebuild the full geometry and motion of a coronal mass ejection (CME). The CME studied erupted on 5 August 2024 from an active region near the Sun's western limb. Their results have been published in Astrophysical Journal Letters.

• VELC's spectra showed emission shifted both towards shorter and towards longer wavelengths, the signature of plasma moving towards and away from the observer at the same time.
• The SDO images traced how the CME moved across the sky, while VELC revealed its motion along the line of sight.
• A model assuming symmetric expansion could not reproduce what VELC saw; only a model with an inclined CME axis and uneven sideways expansion matched the data.

Why it matters for space weather

An uneven early shape changes how a CME meets the solar wind and how much drag it feels while crossing the heliosphere, which alters its speed and therefore when it reaches Earth. Better forecasts matter because such disturbances affect satellites and communication networks.

How VELC works

VELC studies young CMEs by spectroscopy in the green emission line at 530.3 nm, produced by highly ionised iron atoms in the corona. That line comes from hot coronal plasma at about 1.8 million Kelvin, and the Doppler shift of the line gives the plasma's velocity along the line of sight, close to the solar disk. The instrument was designed and fabricated by the IIA at its MGK Menon Lab for Space Sciences on the CREST campus at Hosakote, with substantial support from ISRO. The team now plans to apply the technique to other CMEs, which would let them reconstruct a CME's motion without depending wholly on imaging from more than one vantage point in space.

Saurabh Tripathi, a PhD student at IIA, is the lead author; Tanmoy Samanta, a solar astronomer at IIA, is the corresponding author; and Jayant Joshi of IIA is a co-author.