We have used FORS1 at the ESO VLT to search for light echoes in imaging polarimetry from four historical supernovae in the face-on nearby spiral galaxy M83 (NGC 5236). No echoes were detected around our targets (SN 1923A, SN 1945B, SN 1950B and SN 1957D). This implies that the interstellar medium in their environs is rather tenuous (a few particles/cm^3), possibly as a result of previous supernova explosions that could have cleared the immediate vicinities of our targets. The merits and limitations of searching for light echoes in imaging polarimetry are discussed. From the photometry of the sources detected at the supernova locations, we estimate star cluster masses of 720, 400, 300 Mo for the cluster progenitors of SN 1957D, SN 1923A, and SN 1950B, respectively, and an upper limit of few tens of solar masses for SN 1945B.
تحميل البحث