Composite Grian image of SN 2024acyl taken by Gemini-North Observatory on February 22, 2025. The position of SN 2024acyl is indicated by white ticks. Credit: arXiv (2025). DOI: 10.48550/arxiv.2511.03926
An international team of astronomers has carried out photometric and spectroscopic observations of a distant Type Ibn supernova known as SN 2024acyl. Results of the observation campaign, published November 6 at arXiv preprint server, has shed more light on the properties and origins of this supernova.
Type Ibn supernovae (SNe Ibn) are explosions whose spectra are characterized by low-velocity helium emission lines. They are believed to be core collapse. explosions from massive stars the emissions of which interact with helium-rich circumstellar matter. They also have a relatively high peak brightness and are blue at their peak. Observations indicate that SNe Ibn typically evolve rapidly, with a short rise to peak brightness (less than two weeks) and a subsequent rapid decline.
Far from his master
SN 2024acyl is an ordinary Type Ibn supernova discovered on December 1, 2024 by the Asteroid Last Alert System (ATLAS). It was discovered at a distance of about 398 million light years, with a large estimated offset from its parent galaxy– approximately 114,000 light years.
Following the discovery of SN 2024acyl, a team of astronomers led by Ize Dong of the Harvard-Smithsonian Center for Astrophysics (CfA) began multi-band photometric follow-up observations of the supernova, using primarily the Las Cumbres Observatory global telescope network as well as other ground-based facilities. The study, aimed at investigating the unusual displacement of SN 2024acyl from the host and exploring its nature, was complemented by spectroscopic data.
Overall, the study showed that SN 2024acyl exhibits photometric and spectroscopic characteristics typical of its class. The redshift of SN 2024acyl (about 0.027) was found to match that of CGCG 505-052, making it highly likely that the supernova under study is associated with this galaxy.
Turns out, star formation rate at the explosion site SN 2024 acyl is low. This, together with the star's large displacement, is unusual for the origin of a massive star. Thus, this discovery raises the question of whether all type Ibn SNe come from massive stars.
Runaway star?
According to the study, SN 2024acyl is located at a predicted distance of about 32,500 light-years from the nearest significant light source of the host galaxy. Based on the data collected, astronomers cannot completely rule out the possibility that one of the seven extended sources near SN 2024acyl is its birthplace.
“It is quite possible that the progenitor of SN 2024acyl was a runaway star, ejected from its birthplace either through close encounters in a dense cluster or as a result of a supernova explosion of the main star in a massive binary system,” the researchers concluded.
Overall, by analyzing the population of known Type Ibn SNe, the paper's authors highlighted the diversity of both the environment and spectral properties of these supernovae. They suggest that this may indicate multiple precursor channels for the Ibn SNe type.
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Additional information:
Ize Dong et al., Spectral diversity of type Ibn supernovae and the large offset of the SN2024acyl host, arXiv (2025). DOI: 10.48550/arxiv.2511.03926
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Citation: Exploring the origin of a distant Ibn-type supernova discovered far from its host galaxy (2025, November 13), retrieved November 13, 2025, from https://phys.org/news/2025-11-exploring-distant-ibn-supernova-host.html.
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