A study conducted with the new WEAVE, installed on the Telescopio William Herschel (WHT) at the Observatorio del Roque de los Muchachos (La Palma), and in whose construction the Instituto de Astrofísica de Canarias (IAC) participated, has revealed clear signs of shock interaction in the Type II supernova SN 2023ixf. Almost a year after the explosion, the data obtained with WEAVE reveal complex emission features that provide new clues about the processes shaping the final stages of massive star evolution.
SN 2023ixf, located in the nearby galaxy M101, is the closest Type II supernova discovered in the last decade. Using WEAVE’s large integral field unit, LIFU, a team led by Royal Holloway, University of London, obtained the first supernova spectrum ever captured by this instrument, approximately one year after the outburst. The researchers detected a surprisingly complex hydrogen emission pattern (H-alpha line), with features indicating material moving at extreme velocities—up to 5,650 kilometres per second. These characteristics suggest that the supernova ejecta is colliding with dense shells of circumstellar material (CSM) expelled hundreds of years before the explosion, injecting additional energy into the system. This is the first time such shock interaction signatures have been observed in SN 2023ixf.
These results highlight the potential of WEAVE for detailed spectroscopic studies of transient phenomena. By capturing the shock-driven signatures that shape the evolution of SN 2023ixf, the study provides key insights into how red supergiants lose mass in the centuries leading up to their collapse, enriching our understanding of massive star life cycles.
The Construction of WEAVE
The development of WEAVE was driven by the Isaac Newton Group of Telescopes (ING) following a consultation with the astronomical community regarding the future scientific needs of the WHT. The proposal responded to the consensus on the need for a high-performance, wide-field, multi-object spectrograph capable of complementing, from the ground, the large-scale stellar surveys carried out by space missions such as Gaia (ESA), thereby addressing some of the main astrophysical challenges of the coming decade.
In 2016, the multilateral agreement to design and build WEAVE was signed by the ING consortium countries (the United Kingdom, Spain, and the Netherlands), later joined by France and Italy. Each country contributed key components, and the ING was responsible for auxiliary systems and overall project management. The IAC, in turn, played a crucial role in the development of several key optical components, co-led the design of the focus system with the ING, and actively contributed to project coordination from Spain.
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