Supernova RemnantsThe unprecedented broad bandwidth and
excellent spectral resolution of ASCA has had a major impact on
all areas of research into the nature of supernova remnants
(SNRs). Recent results from ASCA have increased the number of
neutron star/SNR associations, debunking the decade-long mystery
of the paucity of such associations. Additionally, ASCA has
uncovered localized regions of non-thermal X-ray emission inside
of SNRs which are not associated with the synchrotron nebulae
but are produced by previously unrecognized mechanisms. ASCA
maps of SNRs in prominent X-ray emission lines and selected
continuum bands show variation in temperature, ionization,
chemical composition, and, indeed, even the nature of the
underlying emission mechanism. ASCA's increased sensitivity has
allowed for a systematic study of the remnants in the LMC
leading to the discovery of new ejecta-dominated remnants and an
independent measurement of the gas-phase abundances of the LMC.
Highly absorbed Galactic SNRs, which were