The Large Magellanic Cloud Supernova Remnant MCSNR J0550-6823

Abstract

We describe radio, optical, and X-ray observations of this rather faint, old Large Magellanic Cloud (LMC) supernova remnant. The [O iii ] emission forms a distinct shell, the remnant of the outer shock, which encloses the radio and X-ray emission and gives an estimate of age and explosion energy. Because of a collision with an LMC H α filament, radio and X-ray emission are concentrated in the northern half of the remnant. The X-ray spectrum is well fit assuming the plasma is isothermal and in collisional equilibrium. The best-fit temperature is such that almost all energy is in lines from O, Ne, Mg, and Fe. The known distance, low extinction, and low interstellarmedium metallicity allow derivation of masses of several elements produced by the star and in the explosion. The masses of O, Ne, and Fe point to a Type II supernova from the explosion of a 20–25 M _⊙ star. The mass of Mg, however, is higher than that of almost all predictions, but some of this apparent excess might be due to a higher-temperature region in the X-ray-emitting material. Point-like background sources are examined to search for a neutron star, and one possible candidate is found just inside the shell of the remnant.

Keywords

• X-ray astronomy
• Large Magellanic Cloud
• Type II supernovae
• Supernova remnants