High-energy solar-flare activity captured by India’s Aditya-L1 mission, which features onboard X-ray and ultraviolet instruments. The observations include an X6. Three-class flare observed by the Solar Ultraviolet Imaging Telescope (SUIT) on February 22, 2024, showing transmission of flare energy through various layers of the Sun’s atmosphere.
This mission is located close to the Sun – Earth L1 point giving it a permanent view of the Sun thus enabling continuous monitoring of eruptions that potentially impact our space environment.
X6.3 flare observed
The flare was an X6 class. 3 on the scale, making it one of the most powerful classes of solar flares. The SUIT spectrograph detects bright flare kernels in the near-ultraviolet wavelength range of 200–400 nm, and includes signatures from the photosphere and chromosphere.
A flare kernel is still the bright and compact area with energy released by magnetic reconnection deposited into the lower solar atmosphere.
First view of flare kernels
Aditya-L1 spacecraft
This observation presented the most direct view yet of a flare kernel in the Sun’s lower atmosphere. Near-ultraviolet measurements, made by SUIT, indicated that the eruption impacted layers below the chromosphere and nearby photosphere.
This is important, because most of the flare observations hav e been made in those hotter layers that exist above the upper atmosphere. Looking down lower layers allows scientists to follow the journey of energy lose from corona and heats the solar surface.
The instruments on Aditya-L1 can see through different wavelengths, and therefore the scientists were able to compare how the flare looked in ultraviolet and X-ray radiation.
Energy travels through the atmosphere
Combining SUIT observations with those of the Solar Low Energy X-ray Spectrometer, researchers discovered a direct correlation between localized brightening in the lower atmosphere and higher plasma temperature in the corona.
The findings also confirm that energy released in a solar flare spreads through multiple layers of the solar atmosphere rather than being confined to the region where the eruption begins.
High-energy X-ray observations
Aditya-L1’s High Energy L1 Orbiting X-ray Spectrometer, or HEL1OS, has also observed the impulsive phase of solar flares. The instrument recorded high-energy X-rays from flares soon after the spacecraft was launched, and its results were consistent with observations from NOAA’s geostationary satellites.isro.
High-energy X-rays provide information about accelerated particles and the rapid release of magnetic energy during a flare.
Why India’s daylight matters
The spacecraft doesn’t care whether its day or night in India. Aditya-L1 continuously observes the Sun from space while observations from ground based systems in India are limited due to day light, weather and Earth’s atmosphere.
In other words, a solar flare can be detected by the spacecraft from space even if it is not visible from Indian ground stations or optical observatories.
The observations of the mission are thus helpful for real-time watch of solar eruptions and also help to study events which may influence on Earth.
Space-weather implications
Powerful flares can be accompanied by coronal mass ejections—large clouds of magnetised plasma expelled from the Sun. If directed towards Earth, these events can disturb the near-Earth space environment and affect:
- Satellites.
- Radio communications.
- Navigation systems.
- Power grids.
- Aviation communications.
- Astronauts.
- High-frequency radio links.
Improved observations help scientists understand the origins of these eruptions and refine space-weather forecasts.
Aditya-L1 also tracks coronal mass ejections
The Visible Emission Line Coronagraph on board the mission has already detected coronal mass ejections in the solar corona. Researchers saw around 50% coronal dimming, a temperature increase of about 30% and plasma motion related to ejection in the July 16, 2024 event.
Coronal dimming is when material is released from the corona, momentarily making the region look darker. These steps allow researchers to track the time between onset and development of solar eruptions.
Importance of the L1 location
Aditya-L1 is positioned at the first Sun–Earth Lagrange point, approximately 1.5 million kilometres from Earth in the direction of the Sun. This location gives the craft an unobscured view of the solar disc and corona.
Due to its location, instruments onboard are able to sense solar flares and coronal mass ejections prior to their radiation or charged particles impacting Earth. This delivers early warning as well as science data for space-weather monitoring.
A multi-instrument solar observatory
Aditya-L1 carries seven scientific payloads designed to study different aspects of solar activity. These include instruments for:
- Ultraviolet imaging.
- Visible-light coronagraphy.
- Low-energy X-rays.
- High-energy X-rays.
- Solar-wind particles.
- Magnetic fields.
- Solar radiation.
The combination of imaging and spectroscopy enables scientists to study both where a flare occurs and how its energy changes the surrounding plasma.
Growing contribution to solar physics
These observations are an important contribution to international efforts in the field of research on solar flares, coronal heating and space weather from India. The SUIT measurements of these near-ultraviolet flare kernels are particularly useful since the imaging of this wavelength over the entire solar disc had not yet been performed before.
It can enhance models of energy exchange in the corona, chromosphere and photosphere.
What the findings show
Aditya-L1’s flare observations demonstrate that:
- Powerful flares affect multiple atmospheric layers.
- Lower-atmosphere flare kernels can be detected in near-ultraviolet light.
- Coronal heating is linked to energy deposition below the corona.
- X-ray measurements reveal the rapid phase of particle acceleration.
- Continuous space-based solar monitoring is valuable for India.
The mission’s observations will help researchers build a more complete picture of how the Sun releases energy and how those eruptions influence Earth’s space environment.