Past Events

We present first results from the Chandra Large Project observation of the Large Magellanic Cloud (LMC) supernova remnant N132D. N132D was observed in 28 separate observations during 2019 and 2020 totaling more than 878 ks. We compare the new data to archival data acquired in 2006 to measure the expansion of the forward shock in the bright southern rim to be 0. ′′112 ± 0.′′024 over the ∼ 14.15 yr baseline which corresponds to a velocity of 1877 ± 402 km s⁻¹. We measure a shock velocity of 3503 ± 255 km s⁻¹ for a feature in an apparent blowout region in the north-east and use this value to estimate the deceleration of the shock wave in the molecular cloud interaction region. After accounting for the PSF azimuthal difference, the corrected expansion velocity of the southern ring is 1709 ± 386 km s⁻¹, and the velocity of north-east feature is 3738 ± 235 km s⁻¹. The average temperature inferred from X-ray spectral fits to regions in the southern rim is 0.99 keV. It is consistent with the electron temperature implied by the shock velocity we measured, assuming full non-equilibration between electrons and ions. We fitted 1-D evolutionary models for the SNR shock in the Southern rim and Northeast region, using the measured forward shock radius and velocity for propagation into a constant density and power-law profile circumstellar medium. We found good agreement with the age derived from optical measurements of approximately 2500 years, for explosion energies of 1.5 − 2.5 × 10⁵¹ergs and ejecta masses of 2 − 5M⊙ in a constant density medium. We also discuss the model of a shock propagating in a cavity and then interacting with a dense shell of material.