Deep optical imaging of a compact group of galaxies, Seyfert's Sextet

To investigate the dynamical status of Seyfert's Sextet (SS), we have obtained a deep optical (VR + I) image of this group. Our image shows that a faint envelope, down to a surface brightness μoptical(AB) ≃ 27 mag arcsec^-2, surrounds the member galaxies. This envelope is irregular in shape. It is likely that this shape is attributed either to recent-past or to ongoing galaxy interactions in SS. If the member galaxies have experienced a number of mutual interactions over a long timescale, the shape of the envelope should be rounder. Therefore, the irregularly shaped morphology suggests that SS is in an early phase of dynamical interaction among the member galaxies. It is interesting to note that the soft X-ray image obtained with ROSA T (Pildis, Bregman, & Evrard) is significantly similar in morphology. We discuss the possible future evolution of SS briefly.