Dorado and its member galaxies

Context. We are investigating the star formation in galaxies of actively evolving Dorado group where, for a large fraction both early- and late-type galaxies, signatures interactions merging events revealed by optical radio observations. Aims. Our previous H α +[N II] study, probing ≈10 Myr timescales, suggested that is still ongoing early-type galaxies. In this work, we use far-UV (FUV) imaging to map recent on longer order 100 Myr. Methods. used Ultraviolet Imaging Telescope UVIT board Astrosat image backbone previously observed II], with filter FUV.CaF2 (1300–1800 Å). The sample included NGC 1536, 1546, 1549, [CMI2001]4136-01, 1553, IC 2058, PGC 75125, 1566, 1596, 1602; two latter data provided first view far-UV. For others, GALEX, afford ∼5× improvement spatial resolution. Results. emission all observed, tracing young stellar populations ring structures showing tidal distortions. Sérsic index, derived fitting luminosity profiles, always n < 3, suggesting originates from disk also rate (SFR) ranges 0.004 ± 0.001 M ⊙ yr −1 [CMI2001]4136-01 2.455 0.027 1566. Most found at periphery group, where most located. these ratio SFR /SFR close 1, except edge-on similar reported relations local volume samples. however, about 15 times higher than FUV . Dorado’s define separate locus , space respect which well represented relation log (SFR ) = 0.70 × )−1.26. Conclusions. structure emitting discovered early-types implies dissipative processes wet events. systematic discrepancy between SFRs fluxes suggests rejuvenation episodes cannot sustain constant over ∼100 timescales.