Supernova Remnants in the Fossil Starburst in M82

We report the discovery of ten compact H-alpha-bright sources in the post-starburst region northeast of the center of M82, M82 B.'' These objects have H alpha luminosities and sizes consistent with Type II supernova remnants (SNRs). They fall on the same H alpha surface brightness-diameter (Sigma-D) relation defined by SNRs in other nearby star-forming galaxies, with the 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 ~250 pc from the galactic center. If these sources are SNRs, they set an upper limit to the end of the starburst in region B2,‘’ about 500 pc from the galaxy’s core, of ~50 Myr. Region ``B1,‘’ about 1000 pc from the core, lacks good SNR candidates and is evidently somewhat older. This suggests star formation in the galaxy has propagated inward toward the present-day intense starburst core.