A CENTRAL STELLAR REMNANT IN PUPPIS-A

ROSAT observations of a feature in the center of the Puppis A supernov a remnant suggest that it is the stellar remnant of the supernova. Thi s feature has been known since Einstein HRI observations, but convinci ng evidence that it is unresolved has become available only through ob servations from the ROSAT HRI. The source has no optical counterpart t o limiting magnitude B greater than or similar to 25.0, R greater than or similar to 23.6, nor is there an obvious radio counterpart to a li mit of 0.75 mJy at 1.4 GHz. Timing analysis of the X-ray data has indi cated neither pulsations nor variability on long time scales. We sugge st that this source is the cooling neutron-star remnant of the Puppis A progenitor. The similar to 3700 yr age of the supernova remnant woul d make this the youngest known neutron star cooling via thermal proces ses. Assuming it originated at the center of expansion, located 6' to the northeast, requires the stellar remnant to have a transverse veloc ity similar to 1000 km s(-1). The stellar remnant's velocity is direct ed roughly opposite to the average proper motion of the fast, oxygen-r ich knots, believed to be fragments of the progenitor's outer core, wh ich suggests an anisotropic explosion and recoil of a newly formed:neu tron star.