Luke

Utilizing our proper motion measurements in Hovey et al. (2015) of the supernova remnant 0509$-$67.5, we are able to determine a dynamical offset of the explosion site from the geometric center along an approximately east-west dynamical axis where the remnant displays asymmetries in brightness and morphology. We measure projected shock speeds of $5740pm 380$ km s$^{-1}$ to the west and 6370$pm$160 km s$^{-1}$ to the east along our dynamical axis, and a projected diameter of 26.350$pm$0.034$^{primeprime}$ . This measurement is used in a Monte-Carlo simulation of various hydrodynamic models where we find a continuum of dynamical offsets of the explosion site relative to the geometric center based on initial assumptions. In our first scenario, the remnant expands into different ambient medium densities on each side for the entire lifetime of the remnant’s evolution, and we find the offset to be 0.790$pm$0.350$^{primeprime}$ to the west along the dynamical axis. If, however, we model the initial asymmetry to be a result of partitioning the initial explosion energy, we find an offset of 1.370$pm$0.603$^{primeprime}$ in the same direction as the first. Our third scenario is one in which the shock in the west has recently plowed into an over-dense region. This limiting case predicts no dynamical offset of the explosion site from the geometric center. This new determination, along with photometry with wide-band images obtained with the {it Hubble Space Telescope}, reveals 21 stars with I-band magnitudes ranging from 26.90 to 20.51 (assuming an E(B-V) of 0.13) within the 3-$sigma$ error circle of these possible explosion sites. Our results are in contention with the previous claim in Schaefer & Pagnotta (2012), thereby reviving the single degenerate scenario for the progenitor system of the supernova remnant 0509$-$67.5.