Supernova remnants in the fossil starburst in M82

We report the discovery of 10 compact H alpha-bright sources in the poststa rburst region northeast of the center of M82, called M82 B. These objects h ave H alpha luminosities and sizes consistent with Type II supernova remnan ts (SNRs). They fall on the same H alpha surface brightness-diameter relati on (Sigma-D) defined by SNRs in other nearby star-forming galaxies, with th e M82 candidates lying preferentially at the small-diameter end. These are the first candidates for optically visible SNRs in M82 outside the heavily obscured central starburst within about 250 pc from the galactic center. If these sources are SNRs, they set an upper limit to the end of the starburs t in region B2, about 500 pc from the galaxy's core, of about 50 Myr. Regio n B1, about 1000 pc from the core, lacks good SNR candidates and is evident ly somewhat older. This suggests that star formation in the galaxy has prop agated inward toward the present-day intense starburst core.