Spatially Resolved Kinematics and Longslit Spectroscopy of the Young, Oxygen-Rich Supernova Remnant N132D in the Large Magellanic Cloud
We present [O III]λ5007 Fabry-Perot observations of the young, oxygen-rich supernova remnant N132D in the Large Magellanic Cloud that show the detailed two-dimensional velocity field of the remnant with seeing-limited angular resolution. We also present low-dispersion, long slit spectrophotometry at three slit positions across the remnant covering the wavelength range from [O II]λ3727 to [S II]λλ6724. Combining the kinematic and spectral characteristics shown by the line-emitting features in N132D with X-ray and radio observations, we construct a model for the structure of N132D. Many of the high-velocity, O-rich knots appear to be distributed along the surface of an expanding shell, although some of the highest velocity knots lie outside this shell. From the shell's size and motion, we derive an expansion age of ~3150 yr for N132D. Our age estimate is 2.5 times larger than that derived by Lasker and 25% larger than the estimate of Sutherland and Dopita. Quasistationary flocculi are observed in N132D which have radial velocities in the range +/-200 km s^-1^, electron densities greater than ~2000 cm^-3^, and spectral line ratios that indicate the presence of radiative shock waves. We have also mapped the of faint, diffuse emission and find it is largely coincident with the X-ray and radio shells. However, the limb-brightened edge of the diffuse optical emission shell is displaced several arcsec outside the X- ray shell, as previously noticed by Blair et al. We interpret this emission as arising from quiescent ambient gas lying just ahead of the main supernova blast wave that is being ionized by energetic photons produced in the postshock region. Using our kinematic age estimate, the main blast wave, marked by the extent of the X-ray shell with a radius of ~12 pc, is expanding at an average rate of ~3700 km s^-1^.