New density profile and structural parameters of the complex stellar
  system Terzan 5
  Terzan 5 is a globular cluster-like stellar system in the Galactic Bulge
which has been recently found to harbor two stellar populations with different
iron content and probably different ages (Ferraro et al. 2009). This discovery
suggests that Terzan 5 may be the relic of a primordial building block which
contributed to the formation of the Galactic Bulge. Here we present a
re-determination of the structural parameters (center of gravity, density and
surface brightness profiles, total luminosity and mass) of Terzan 5, as
obtained from the combination of high-resolution (ESO-MAD and HST ACS-WFC) and
wide-field (ESO-WFI) observations. We find that Terzan 5 is significantly less
concentrated and more massive than previously thought. Still it has the largest
collision rate of any stellar aggregate in the Galaxy. We discuss the impact of
these findings on the exceptional population of millisecond pulsars harbored in
this stellar system.
