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Context. SN 2023ixf was discovered in Galaxy M101 in May 2023. Its proximity made it an extremely valuable opportunity for the scientific community to study the characteristics of the SN and its progenitor. A point source detected on archival images and hydrodynamical modelling of the bolometric light curve has been used to constrain the former star's properties. There is a significant variation in the published results regarding the initial mass of the progenitor. Nebular spectroscopy provides an independent tool to enhance our understanding of the supernova and its progenitor. Aims. We determine the SN progenitor mass by studying the first published nebular spectrum taken 259 days after the explosion. Methods. We analyze the nebular spectrum taken with GMOS at the Gemini North Telescope. Typical emission lines are identified, such as O I, H, Ca II, among others. Some species' line profiles show broad and narrow components, indicating two ejecta velocities and an asymmetric ejecta. We infer the progenitor mass of SN 2023ixf by comparing with synthetic spectra and by measuring the forbidden oxygen doublet flux. Results. Based on the flux ratio and the direct comparison with spectra models, the progenitor star of SN 2023ixf had a Mₙ₀₌ₒ between 12 and 15 M_. In comparison with this, we find the use of the O I doublet flux to be less constraining of the progenitor mass. Our results agree with those from hydrodynamical modelling of the early light curve and pre-explosion image estimates pointing to a relatively low-mass progenitor.
Ferrari et al. (Fri,) studied this question.