  Oxygen-rich young supernova remnants are valuable objects for probing the
outcome of nucleosynthetic processes in massive stars, as well as the physics
of supernova explosions. Observed within a few thousand years after the
supernova explosion, these systems contain fast-moving oxygen-rich and
hydrogen-poor filaments visible at optical wavelengths: fragments of the
progenitor's interior expelled at a few 1000 km/s during the supernova
explosion. Here we report the first identification of the compact object in
1E0102.2-7219 in reprocessed Chandra X-ray Observatory data, enabled via the
discovery of a ring-shaped structure visible primarily in optical recombination
lines of Ne I and O I. The optical ring, discovered in integral field
spectroscopy observations from the Multi Unit Spectroscopic Explorer (MUSE) at
the Very Large Telescope, has a radius of $(2.10\pm0.35)$ arcsec =
$(0.63\pm0.11)$ pc, and is expanding at a velocity of $90.5_{-30}^{+40}$ km/s.
It surrounds an X-ray point source with an intrinsic X-ray luminosity $L_{i}$
(1.2--2.0 keV)= $(1.4\pm0.2)\times10^{33}$ erg/s. The energy distribution of
the source indicates that this object is an isolated neutron star: a Central
Compact Object akin to those present in the Cas A and Puppis A supernova
remnants, and the first of its kind to be identified outside of our Galaxy.
