A study of the ionized gas in Stephan's Quintet from integral field
  spectroscopy observations
  The Stephan's Quintet (SQ) is a famous interacting compact group of galaxies
in an important stage of dynamical evolution, but surprisingly very few
spectroscopic studies are found in the literature. We present optical integral
field spectroscopy (IFS) observations of the SQ from the PPAK IFS Nearby
Galaxies Survey (PINGS), that provide a powerful way of studying with spatial
resolution the physical characteristics of the ionized gas within the group.
The nature of the gas emission is analysed using 2D maps of
continuum-subtracted, pure emission-line intensities, stacked spectra,
diagnostic diagrams, and photoionization model predictions. In the case of NGC
7319, we study the galaxy-wide high-velocity outflow emission by comparing the
emission properties with theoretical shock and AGN models. We conclude that the
excitation mechanism of the gas in this galaxy is a mixture of AGN
photoionization and shocks with a photoionizing precursor. The emission spectra
from the large scale shock front in the interacting pair NGC 7318A/B is
analysed, confirming the presence of several kinematic components. Comparison
with predictions from theoretical shock models suggests that the gas emission
is consistent with shocks without a photoionizing precursor, low pre-shock
density, and velocities in the range of 200 - 400 km s-1. The gas oxygen
abundance for NGC 7318B is determined using an updated O3N2 calibration.
Although NGC 7317 shows no significant gas emission, an ionizing cluster is
found southwest of this galaxy, probably the result of tidal interaction. As a
by-product, we analyse the gas emission of the foreground galaxy NGC 7320.
