Investigating early-type galaxy evolution with a multiwavelength approach II. The UV structure of 11 galaxies with Swift-UVOT

Context. GALEX detected a significant fraction of early-type galaxies, in particular S0s, showing far-UV bright structures, sometimes involving an entire galaxy out to its outskirts. These features suggest the presence of either recent ongoing and /or prolonged star formation episodes, shedding new light on the evolution of these systems. Aims. We aim at understanding the evolutionary path[s] of these early-type galaxies and the mechanisms at the origin of their UVbright structures. We investigate with a multiwavelength approach the link between the inner and outer galaxy regions of a set of 11 early-type galaxies that were selected because of their nearly passive stage of evolution in the nuclear region. Methods. This paper, second of a series, focuses on the information coming from the comparison between UV features detected by Swift-U V O T, which trace recent star formation, and the galaxy optical structure, which maps older ersic indices are usually higher than in the UV indices. (M2 V) color profiles are bluer in ring-or arm-like structures than in the galaxy body. Conclusions. The lower values of SErsic indices in the UV bands with respect to optical bands, suggesting the presence of a disk, point out that the role of the dissipation cannot be neglected in recent evolutionary phases of these early-type galaxies.