Historic First: ADITYA-L1
India’s Solar Ultra-violet Imaging Telescope (SUIT) onboard Aditya-L1 Captures Unprecedented Solar Flare Details
By R Anil Kumar
Bengaluru, February 28. Aditya-L1, India’s first dedicated space based solar mission, has made a ground-breaking observation from its scientific payloads- capturing the first-ever image of a solar flare ‘kernel’ in the lower solar atmosphere, namely the photosphere and the chromosphere, in the images recorded in the Near Ultra-violet (NUV) band. This observation and associated scientific results marks a major step in understanding the Sun’s explosive activity and its impact on Earth.
Aditya-L1 mission was launched on September 2, 2023 by ISRO PSLV C-57 rocket. On January 6, 2024 the spacecraft was successfully placed in a large halo orbit around first Earth-Sun Lagrange Point known as Lagrange Point L1.
The L1 point is 1.5 million kilometres away from Earth towards the Sun. The special vantage point L1 allows the spacecraft to continuously observe various solar activities without any eclipse and occultation’s.
Its advanced instruments, including Solar Ultraviolet Imaging Telescope (SUIT), Solar Low Energy X-ray Spectrometer (SoLEXS), and High Energy L1 Orbiting X-ray Spectrometer (HEL1OS), work together to detect and analyse solar flares from Near Ultra-violet (NUV) wavelength to soft and hard X-rays.
SUIT payload is developed by Inter University Centre for Astronomy and Astrophysics (IUCAA) in close collaborations with various ISRO Centres. SoLEXS and HEL1OS payloads are developed by U Rao Satellite Centre (URSC), Bengaluru.
SUIT can capture high-resolution images in 11 different waveband in NUV of the full solar disk or a specific region on the solar disk of scientific interest depending upon the scientific requirements.
As different radiations of different wavelength leave the solar atmosphere from different height/layers, it allows scientists to study multiple layers of the Sun’s atmosphere to study their coupling and dynamics.
SoLEXS and HEL1OS instruments monitor solar X-ray emissions, which help detecting the solar flare activity. This collaborative approach and joint data analysis from different instruments of Aditya-L1, gives scientists a complete picture of how solar energy moves through different layers of the Sun.
What is a Solar flare?
A solar flare is a sudden and intense burst of solar energy from the Solar atmosphere. The phenomena is caused by Sun’s magnetic field. The magnetic field of the Sun is very dynamic in nature. Sometime they suddenly snap and release intense burst of energy – like a powerful, short flash. The energy is released in the form of light/radiation and high energy charged particles.
How Aditya-L1 study the Solar flares?
During solar flare (as well as before the occurrence of solar flare) that particular region of the Sun generating flare becomes brighter in UV and X-ray. Aditya-L1 instruments such as SUIT, SoLEXS and HEL1OS can study these brightening and associated flash of radiation in greater details. This provides a detail picture of various phenomena related to Solar flares. It is to be noted that atmosphere of the Earth blocks these harmful radiations from the Sun to reach to the ground. Therefore, such study can be only made from space.
What did researchers observe from SUIT on-board Aditya-L1?
On February 22, 2024, the SUIT payload onboard Aditya-L1 observed an X6.3-class solar flare, which is one of the most intense categories of solar eruptions. The unique feature of this observation was that SUIT detected brightening in NUV wavelength range (200-400 nm) —a wavelength range never observed before in such greater detail (See Figure below). These observations confirm that the energy released from the flare spread through different layers of the Sun’s atmosphere. This provides new insights into the complex physics responsible for these massive solar explosions.
One of the most exciting revelations in this observation is that thelocalized brightening captured in the lower Solar atmosphere corresponds directly with an increase in the temperature of plasma in the Solar corona at the top of the solar atmosphere. This confirms the linkage between flare energy deposition and associated temperature evolution. This finding also validates long-standing theories while offering new data that will help to reshape our understanding of physics of solar flare.
Top Image: This figure shows the observations in SUIT narrow band NB04 filter, 280 nanometre (nm) wavelength, which shows the flaring region and the sunspot. The blue box shown in this figure mark the Region of Interest (RoI) of this observation. The region marked with white dashed box shows the region that was used for subsequent analysis by other filters of SUIT payload.
Bottom Image: The size of the images shown here corresponds to the white box region shown in the top figure for detail analysis. SUIT observed two bright kernels in various channels marked by arrows. The appearance of these bright kernels in NB02 and NB05 is highly interesting as these two filters observe the solar photosphere, which is lower than the chromospheric emissions Magnesium II and Calcium II. This implies that the effect of this flare affected the layers below the chromosphere. The images are taken in various narrow band (NB) filters of SUIT and are shown with various numbers in the figure. These corresponds to the wavelengths 214 nm (NB01), 276 nm (NB02), 279 nm (NB03), 280 nm (NB04), 283 nm (NB05), 300 nm (NB06), 388 nm (NB07), 396 nm (NB08).
