The Physical Parameters of the Micro-quasar S26 in the Sculptor Group
  Galaxy NGC 7793
  NGC 7793 - S26 is an extended source (350 pc $\times$ 185 pc) previously
studied in the radio, optical and x-ray domains. It has been identified as a
micro-quasar which has inflated a super bubble. We used Integral Field Spectra
from the Wide Field Spectrograph on the ANU 2.3 m telescope to analyse spectra
between 3600--7000 \AA. This allowed us to derive fluxes and line ratios for
selected nebular lines. Applying radiative shock model diagnostics, we estimate
shock velocities, densities, radiative ages and pressures across the object. We
show that S26 is just entering its radiative phase, and that the northern and
western regions are dominated by partially-radiative shocks due to a lower
density ISM in these directions. We determine a velocity of expansion along the
jet of 330 km s$^{-1}$, and a velocity of expansion of the bubble in the minor
axis direction of 132 km s$^{-1}$. We determine the age of the structure to be
$4.1\times10^5$ yr, and the jet energy flux to be $ (4-10)\times10^{40}$ erg
s$^{-1}$ The jet appears to be collimated within $\sim0.25$ deg, and to undergo
very little precession. If the relativistic $\beta \sim 1/3$, then some 4
M$_{\odot}$ of relativistic matter has already been processed through the jet.
We conclude that the central object in S26 is probably a Black Hole with a mass
typical of the ultra-luminous X-ray source population which is currently
consuming a fairly massive companion through Roche Lobe accretion.
