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Historic First: Capturing the Unprecedented details of Solar Flares with the Solar Ultraviolet Imaging Telescope (SUIT) onboard Aditya-L1



The Solar Ultraviolet Imaging Telescope (SUIT) on board the Aditya-L1 mission -- India's first dedicated solar space mission captures a solar flare ‘kernel’ in the lower solar atmosphere, namely the photosphere and the chromosphere, in the images recorded in the near-ultraviolet (NUV) band. This ground-breaking observation marks a leap in the understanding of explosive activities in the solar atmosphere.

The SUIT instrument onboard Aditya-L1 observed an X6.3-class solar flare on February 22, 2024, one of the most intense categories of solar eruptions. The uniqueness of this discovery lies in the fact that SUIT detected brightening in the near ultraviolet wavelength range (200-400 nm) (See Figure 1). The Sun's full disk has never been imaged in this entire wavelength range in such detail. These observations provide new insights into these huge eruptions in the solar atmosphere and highlight the complex physical processes involved in the transfer of mass and energy through different layers of the solar atmosphere.

Solar flares release huge bursts of radiation and energetic particles by sudden release of magnetic energy stored in the complex solar magnetic field. Such events can have a serious impact on space weather and geo-space, including disrupting radio communications, affecting satellite operations, interfering with power grids, posing risks to astronauts and airline passengers.

Solar flares have been studied for over a century since they were first observed by Carrington and Hodgson (1850) from the ground. However, their properties in the near-ultraviolet band were nearly non-existent, primarily due to a lack of dedicated space telescopes in this wavelength band. Ground-based telescopes cannot make these measurements as the ultraviolet radiation gets absorbed by the Earth's atmosphere. The SUIT instrument on board Aditya-L1 is, for the first time, providing these ever-missing observations, revealing never-before-seen insights into the complex dynamics of solar flares and the processes at play in the transfer of mass and energy across the different layers of the solar atmosphere.

The detection of localized brightening in the images recorded by SUIT that directly corresponds with the increase in temperature of the plasma in the solar corona at the top of the atmosphere is one of the most exciting revelations. This provides the direct link between the heating of the plasma and flare energy deposition (See Fig. 2). While these results validate the long-standing theoretical predictions, they also offer new avenues for reshaping our understanding of complex physics at play in solar flare dynamics.

Aditya-L1 spacecraft, India's first dedicated space mission for solar studies, was launched on September 02, 2023, and successfully injected into a halo orbit around the first Lagrange point L1. This location is 1.5 million kilometres away from Earth. The special location allows the spacecraft to observe the Sun continuously 24x7 without any interruption. For solar flare studies in near real-time, its advanced instruments, including SUIT, Solar Low Energy X-ray Spectrometer (SoLEXS), and High Energy L1 Orbiting Spectrometer (HEL1OS), work in tandem. The high-resolution images captured by SUIT in 11 different filters allow us to study multiple layers of the solar atmosphere. SoLEXS and HEL1OS monitor solar X-ray emissions, helping detect flare activity. This collaborative approach gives scientists a complete picture of how solar energy moves through the Sun's layers.

Ph.D. student Mr. Soumya Roy leads this pioneering research under the guidance of Prof. Durgesh Tripathi and Prof. A. N. Ramaprakash at the Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, India. The research team includes other experts from IUCAA, Manipal Academy for Higher Education (MAHE), UR Rao Satellite Centre / ISRO, Centre for Excellence in Space Science India (IISER-Kolkata), Max-Planck Institute for Solar System Research, Germany, Indian Institute of Space Science and Technology (IIST), Thiruvananthapuram and the SoLEXS team from UR Rao Satellite Centre / ISRO. The findings are published in The Astrophysical Journal Letters, one of the world’s leading astrophysics journals (DOI: 10.3847/2041-8213/adb0be).

Looking Ahead

With SUIT and other instruments now fully operational, Aditya-L1 is set to revolutionize our understanding of the Sun and its influence on space weather. This marks just the beginning of what could be a new era in solar physics, with India leading the way in uncovering the Sun's deepest secrets.

Figuer 1
Figure 1: Observation of the flare as obtained from various SUIT filters. 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.



Figuer 2
Figure 2: Light curves obtained over the contoured region from AIA 1600 (blue dashed), AIA 1700 ˚A (black do-dashed), NB03 (black dotted), NB04 (green dot-dashed), NB08 (magenta dashed), NB02 (blue dotted), NB05 (green dashed), NB01 (green triangles), NB06 (magenta squares) and NB07 (blue dotted) as labelled. For comparison, we have also over-plotted the light curves obtained from coaligned GONG H-alpha observations (blue squares) in panel (b), full-sun integrated GOES/SXR in 1–8 ˚A (red solid) and STIX/HRX (black dashed) in panel (d). IN panel (f), we show the lightcurve obtained from SoLEXS 2–20keV (black) observations and the calculated temperature (blue) and emission measure (red)



Ph.D. Student and lead author Mr Soumya Roy says: “The February 22nd, 2024, solar flare was a powerful reminder of the Sun's dynamic nature. Using SUIT, we observed a large solar flare in specific near-ultraviolet wavelengths for the first time in human history. The bright kernels we detected suggest a previously unseen response of the lower solar atmosphere, offering new insights into flare dynamics. Working with such unique observations early in my scientific career is an exciting opportunity. It is a great honour to contribute to developing the country's first observatory-class solar mission and utilise it to showcase the first scientific results.”

Principal Investigator of SUIT and lead scientist Prof Durgesh Tripathi says: “For the first time, we are witnessing the Sun's explosive power in unprecedented detail, unveiling secrets hidden in the near ultraviolet wavelength. SUIT's breakthrough observations mark a transformative moment in solar physics, allowing us to trace the physics of solar flares and uncover the complex processes driving energy and mass transfer throughout the solar atmosphere. With Aditya-L1 and in particular with SUIT instrument, we are entering into a new era of solar exploration.”

Instrument Principal Investigator and Payload Manager Prof A N Ramaprakash says: “These first results demonstrate how a novel instrument could help in making new discoveries. The flare discussed in this paper is one of the earliest ones detected by SUIT on-board Aditya-L1. The observations provide new evidence for how activities in the Solar atmosphere are interrelated across widely separated layers.”

IUCAA Director Prof Srianand says: “It is indeed a great feeling to see the SUIT providing new insights on solar flares through multiple UV band images. I am sure this is one of the many important findings SUIT will provide in the coming days. I wish the SUIT team and other members of the Aditya-L1 science team all the very best.”

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Research contacts:

Mr. Soumya Roy Mr. Soumya Roy
IUCAA, Pune


E-mail: soumyaroy_at_iucaa.in
Prof. Durgesh Tripathi Prof. Durgesh Tripathi
IUCAA, Pune


E-mail: durgesh_at_iucaa.in
Prof. A. N. Ramprakash Prof. A. N. Ramaprakash
IUCAA, Pune


E-mail: anr_at_iucaa.in
* please change _at_ to @