SIMBAD references

The progenitors of Type II-P supernovae (SNe) are generally considered to be red supergiants. SN 2009ib and SN 2012ec are two Type II-P SNe for which progenitor candidates have been identified in preexplosion images. In this work, we use new, late-time Hubble Space Telescope observations to search for the disappearance of these two candidates and confirm their nature. In the case of SN 2009ib, the late-time high-resolution imaging reveals that the progenitor candidate is in fact a blend of multiple unresolved stars. Subsequent difference imaging shows no significant change in brightness at the SN's position, even years after the explosion. These findings indicate that the flux from the previously identified source is dominated by unresolved field stars, with little to no contribution from the genuine progenitor. Taking advantage of new observational data and methods, we constrained the progenitor mass of SN 2009ib to an upper limit of ∼10 M_⊙. In the case of SN 2012ec, a comparison of preexplosion and late-time images reveals that the progenitor candidate faded by about 0.6 mag in the F814W band 7 yr after the explosion, confirming the disappearance of the progenitor.