In a historic first, the Solar Ultraviolet Imaging Telescope (SUIT) onboard Aditya-L1 has succeeded in capturing unprecedented details of solar flares. SUIT is a unique space telescope developed by the Inter-University Centre for Astronomy and Astrophysics (IUCAA) Pune, and launched by ISRO whereas Aditya-L1 is India’s first dedicated solar space mission.
SUIT has succeeded in capturing a solar flare ‘kernel’ in the lower solar atmosphere, namely the photosphere and the chromosphere in 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 pioneering research is led by Ph.D. student Soumya Roy under the guidance of professor Durgesh Tripathi and professor A N Ramaprakash at the IUCAA Pune. 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 have been published in The Astrophysical Journal Letters, one of the world’s leading astrophysics journals.
SUIT 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).
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.
Lead author Soumya Roy said, “The February 22, 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 professor Durgesh Tripathi said, “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 the SUIT instrument, we are entering a new era of solar exploration.”
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, and 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 onboard 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 localised 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. While these results validate long-standing theoretical predictions, they also offer new avenues for reshaping our understanding of complex physics at play in solar flare dynamics.
Aditya-L1 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 24×7 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.
Instrument principal investigator and payload manager professor A N Ramaprakash said, “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 said, “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.”
With SUIT and other instruments now fully operational, Aditya-L1 is set to revolutionise 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.
Figure caption: 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.