A Central Stellar Remnant in Puppis A

Abstract

ROSAT observations of a feature in the centerof the Puppis A supernova remnant suggest that it is the stellarremnant of the supernova. This feature has been known since EinsteinHRI observations, but convincing evidence that it is unresolved hasbecome available only through observations from the ROSAT HRI. Thesource has no optical counterpart to limiting magnitude B >~ 25.0, R>~ 23.6, nor is there an obvious radio counterpart to a limit of0.75 mJy at 1.4 GHz. Timing analysis of the X-ray data has indicatedneither pulsations nor variability on long time scales. We suggestthat this source is the cooling neutron-star remnant of the Puppis Aprogenitor. The ~3700 yr age of the supernova remnant would make this theyoungest known neutron star cooling via thermal processes. Assuming itoriginated at the center of expansion, located 6' to the northeast,requires the stellar remnant to have a transverse velocity ~1000 kms-1. The stellar remnant's velocity is directed roughly opposite tothe average proper motion of the fast, oxygen-rich knots, believedto be fragments of the progenitor's outer core, which suggests ananisotropic explosion and recoil of a newly formed neutron star.