Hubble Space Telescope observations of oxygen-rich supernova remnants in the Magellanic Clouds.: II.: Elemental abundances in N132D and 1E 0102.2-7219

We present Hubble Space Telescope (HST) Wide Field and Planetary Camera 2 images and Faint Object Spectrograph data of two young supernova remnants in the Magellanic Clouds, N132D (LMC) and 1E 0102.2-7219 (SMC). The spectra cover essentially the entire UV/optical range available to HST and provide the first true comparison of UV/optical line intensities from astrophysical shocks that do not depend on scalings from different aperture sizes or instruments. For the spectra, we isolated specific knots and filaments that contain fast-moving debris of nuclear-processed material that are devoid of hydrogen and appear to have originated from the cores of the progenitor stars. In N132D we also observed a knot on the outer rim of the remnant that represents a shocked interstellar cloud. In the debris from both remnants, we identify only the elements O, Ne, C, and Mg. We find no evidence for oxygen-burning products, such as S, Ca, Ar, etc., which are seen in Cas A and are expected from models of Type II supernovae. We suggest that the progenitor stars of N132D and 1E 0102.2-7219 had large, oxygen-rich mantles (perhaps Wolf-Rayet stars) and may be the products of Type Ib supernovae. Shock modeling demonstrates systematic differences in the relative abundances in the O-rich debris, possibly pointing to different progenitor masses for these two objects. The shocked interstellar knot in N132D shows that we are probably seeing a range of conditions within the similar to 1 " aperture and that no evidence is present for enrichment by a precursor star wind.