SN 2024ggi: Another year, another striking Type II supernova

Abstract

Context. SN 2024ggi is a Type II supernova that exploded in the nearby galaxy NGC 3621 at a distance of approximately 7 Mpc, making it one of the closest supernovae of the decade. It shows clear signs of interaction with a dense circumstellar material (CSM), and several studies have investigated the properties of its possible progenitor star using pre-explosion data.Aims. We aim to constrain the progenitor properties of SN 2024ggi by performing hydrodynamical modelling of its bolometric light curve and expansion velocities using our own spectrophotometric data.Methods. We present photometric and spectroscopic observations of SN 2024ggi obtained with the Complejo Astronómico El Leoncito, with Las Campanas Observatory, and with Las Cumbres Observatory Global Telescope Network spanning from 2 to 106 days after explosion. We constructed its bolometric light curve and characterised it by calculating its morphological parameters. Then, we computed a grid of one-dimensional explosion models for evolved stars with varying masses and estimated the properties of the progenitor star of SN 2024ggi by comparing the models to the observations.Results. The observed bolometric luminosity and expansion velocities are well matched by a model that includes the explosion of a star in the presence of a close CSM, with a zero-age main sequence mass of MZAMS = 15 M⊙, a pre-supernova mass and radius of 14.1 M⊙ and 517 R⊙, respectively, an explosion energy of 1.2 × 1051 erg, and a nickel mass below 0.035 M⊙. Models of MZAMS = 13 M⊙ and 18 M⊙ were unable to reproduce the observations. Our analysis suggests that the progenitor suffered a mass-loss rate of 4 × 10−3 M⊙ yr−1 within a radius of 3000 R⊙. The CSM distribution is likely a two-component structure that consists of a compact core and an extended tail. This analysis represents the first hydrodynamical model of SN 2024ggi with a complete coverage of the plateau phase.