New insights on Stephan's Quintet: exploring the shock in three dimensions

The authors study the ionized gas emission from the large scale shock region of Stephan's Quintet (SQ). They carried out integral field unit optical spectroscopy on three pointings in and near the SQ shock. They used Potsdam MultiAperture Spectrometer on the 3.5 m Calar Alto telescope to obtain measures of emission lines that provide insight into physical properties of the gas. Severe blending of H alpha and NII lambda 6548, 6583 Aa emission lines in many spaxels required the assumption of at least two kinematical components to extract fluxes for the individual lines. The main results from their study include: 1. detection of discrete emission features in the new intruder velocity range 5400 km s super( -1)-6000 km s super( -1) showing properties consistent with HII regions, 2. detection of a low-velocity component spanning the range 5800 km s super( -1)-6300 km s super(-1) with properties resembling a solar-metallicity shocked gas and 3. detection of a high-velocity component at approximately 6600 km s super( -1) with properties consistent with those of a low-metallicity shocked gas.