We study the IB(s)m galaxy IC 3476 observed in the context of the Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE), a blind narrow-band Hα+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT. The deep narrow-band image reveals a very pertubed ionised gas distribution that is characterised by a prominent banana-shaped structure in the front of the galaxy formed of giant HII regions crossing the stellar disc. Star-forming structures, at ∼8 kpc from the edges of the stellar disc, are also detected in a deep far-ultraviolet ASTROSAT/UVIT image. This particular morphology indicates that the galaxy is undergoing an almost edge-on ram pressure stripping event. The same Hα+[NII] image also shows that the star formation activity is totally quenched in the leading edge of the disc, where the gas has been removed during the interaction with the surrounding medium. The spectral energy distribution fitting analysis of the multi-frequency data indicates that this quenching episode is very recent (∼50 Myr), and roughly corresponds to an increase of the star formation activity by a factor of ∼161% in the inner regions with respect to that expected for secular evolution. The analysis of these data, whose angular resolution enables the study of the induced effects of the perturbation down to the scale of individual HII regions (req ≃ 40 pc), also suggests that the increase of star formation activity is due to the compression of the gas along the stellar disc of the galaxy, which is able to increase its mean electron density and boost the star formation process producing bright HII regions with luminosities up to L(Hα) ≃ 1038 erg s−1. The combined analysis of the VESTIGE data with deep IFU spectroscopy gathered with MUSE and with high spectral resolution Fabry Perot data also indicates that the hydrodynamic interaction has deeply perturbed the velocity field of the ionised gas component while leaving that of the stellar disc unaffected. The comparison of the data with tuned high-resolution hydrodynamic simulations accounting for the different gas phases (atomic, molecular, ionised) consistently indicates that the perturbing event is very recent (50–150 Myr), once again confirming that ram pressure stripping is a violent phenomenon that is able to perturb the evolution of galaxies in rich environments on short timescales.

Abstract. We present Fabry Perot observations of galaxies in five Hickson Compact Groups: HCG 10, HCG 19, HCG 87, HCG 91 and HCG 96. We observed a total of 15 galaxies and we have detected ionized gas for 13 of them. We were able to derive 2D velocity, monochromatic, continuum maps and rotation curves for the 13 objects. Almost all galaxies in this study are late-type systems; only HCG 19a is an elliptical galaxy. We can see a trend of kinematic evolution within a group and among different groups -from strongly interacting systems to galaxies with no signs of interaction -HCG 10 exhibits at least one galaxy strongly disturbed; HCG 19 seems to be quite evolved; HCG 87 does not show any sign of merging but a possible gas exchange between two galaxies; HCG 91 could be accreting a new intruder; HCG 96 exhibits past and present interactions.

We present kinematic and photometric evidence for the presence of seven candidate tidal dwarf galaxies in Stephan's quintet. The central regions of the two most probable parent galaxies, N7319 and N7318B, contain little or no gas whereas the intragroup medium, and particularly the optical tails that seem to be associated with N7318B are rich in cold and ionized gas.Two tidal-dwarf candidates may be located at the edge of a tidal tail, one within a tail and for four others there is no obvious stellar/gaseous bridge between them and the parent galaxy. Two of the candidates are associated with HI clouds, one of which is, in addition, associated with a CO cloud. All seven regions have low continuum fluxes and high Hα luminosity densities (F(Hα) = 1 -60 × 10 −14 erg s −1 cm −2 ). Their magnitudes (M B = -16.1 to -12.6), sizes (∼ 3.5 h −1 75 kpc), colors (typically B−R = 0.7) and gas velocity gradients (∼ 8 -26 h 75 km s −1 kpc −1 ) are typical for tidal dwarf galaxies. In addition the ratios between their star formation rates determined from Hα and from the B band luminosity are typical of other tidal dwarf galaxies. The masses of the tidal dwarf galaxies in Stephan's quintet range from ∼ 2 × 10 8 to 10 10 M ⊙ and the median value for their inferred mass-to-light ratios is 7 M ⊙ /L ⊙ .At least two of the systems may survive possible "fall-backs" or disruption by the parent galaxies and may already be or turn into self-gravitating dwarf galaxies, new members of the group.

We obtained new Fabry-Perot data cubes and derived velocity fields, monochromatic, and velocity dispersion maps for 28 galaxies in the Hickson compact groups 37, 40, 47, 49, 54, 56, 68, 79, and 93. We also derived rotation curves for 9 of the studied galaxies, 6 of which are strongly asymmetric. Combining these new data with previously published 2D kinematic maps of compact group galaxies, we investigated the differences between the kinematic and morphological position angles for a sample of 46 galaxies. We find that one third of the unbarred compact group galaxies have position angle misalignments between the stellar and gaseous components. This and the asymmetric rotation curves are clear signatures of kinematic perturbations, probably because of interactions among compact group galaxies. A comparison between the B-band Tully-Fisher relation for compact group galaxies and for the GHASP field-galaxy sample shows that, despite the high fraction of compact group galaxies with asymmetric rotation curves, these lay on the TF relation defined by galaxies in less dense environments, although with more scatter. This agrees with previous results, but now confirmed for a larger sample of 41 galaxies. We confirm the tendency for compact group galaxies at the low-mass end of the Tully-Fisher relation (HCG 49b, 89d, 96c, 96d, and 100c) to have either a magnitude that is too bright for its mass (suggesting brightening by star formation) and/or a low maximum rotational velocity for its luminosity (suggesting tidal stripping). These galaxies are outside the Tully Fisher relation at the 1σ level, even when the minimum acceptable values of inclinations are used to compute their maximum velocities. Including such galaxies with v < 100 km s −1 in the determination of the zero point and slope of the compact group B-band Tully-Fisher relation would strongly change the fit, making it different from the relation for field galaxies, which has to be kept in mind when studying scaling relations of interacting galaxies, especially at high redshifts.