  We use a deep Chandra observation to examine the structure of the hot
intra-group medium of the compact group of galaxies Stephan's Quintet. The
group is thought to be undergoing a strong dynamical interaction as an
interloper, NGC 7318b, passes through the group core at ~850 km/s. A bright
ridge of X-ray and radio continuum emission has been interpreted as the result
of shock heating, with support from observations at other wavelengths. We find
that gas in this ridge has a similar temperature (~0.6 keV) and abundance (~0.3
solar) to the surrounding diffuse emission, and that a hard emission component
is consistent with that expected from high-mass X-ray binaries associated with
star-formation in the ridge. The cooling rate of gas in the ridge is consistent
with the current star formation rate, suggesting that radiative cooling is
driving the observed star formation. The lack of a high-temperature gas
component is used to place constraints on the nature of the interaction and
shock, and we find that an oblique shock heating a pre-existing filament of HI
may be the most likely explanation of the X-ray gas in the ridge. The mass of
hot gas in the ridge is only ~2 per cent of the total mass of hot gas in the
group, which is roughly equal to the deficit in observed HI mass compared to
predictions. The hot gas component is too extended to have been heated by the
current interaction, strongly suggesting that it must have been heated during
previous dynamical encounters.
