The Red Supergiant Progenitor of Type II Supernova 2024ggi

We present a detailed analysis of the progenitor and its local environment for the recently discovered type II supernova (SN) 2024ggi at a distance of about 6.7 Mpc, by utilizing the pre-explosion images from the Hubble Space Telescope (HST) and Spitzer Space Telescope. The progenitor is identified as a red, bright variable star, with absolute F814W-band magnitudes being -6.2 mag in 1995 to -7.2 mag in 2003, respectively, consistent with that of a normal red supergiant (RSG) star. Combining with the historical mid-infrared light curves, a pulsational period of about 379 days can be inferred for the progenitor star. Fitting its spectral energy distribution with stellar spectral models yields the stellar parameters of temperature, radius and bolometric luminosity as T_*=3290_-27^+19 K, R_*=887_-51^+60 R_⊙, and log(L/L_⊙)=4.92_-0.04^+0.05, respectively. The above parameters indicate that the progenitor of SN 2024ggi is consistent with the stellar evolutionary track of a solar-metallicity massive star with an initial mass of 13_-1^+1 M_⊙. Moreover, our analysis indicates a relatively low mass loss rate (i.e., < 3×10^-6 M_⊙ yr^-1) for the progenitor compared to that inferred from the flashed spectra and X-ray detection (i.e., 10^-2-10^-5 M_⊙ yr^-1), implying a significant enhancement in mass loss within a few years prior to the explosion.