J/A+A/664/A192ivo://CDS.VizieR/J/A+A/664/A192doi:10.26093/cds/vizier/bc-mr/lbjcCDSRampazzo R.Mazzei P.Marino A.Bianchi L.Postma J.Ragusa R.,Spavone M.Iodice E.Ciroi S.Held E.V.2026-07-01T14:00:25Z2022-08-30T11:48:02ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgalaxy-clustersgalaxiesultraviolet-astronomyWe are investigating the star formation in galaxies of the actively evolving Dorado group where, for a large fraction of both early- and late-type galaxies, signatures of interactions and merging events are revealed by optical and radio observations. Our previous H{alpha}+[NII] study, probing ~10Myr timescales, suggested that star formation is still ongoing in early-type galaxies. In this work, we use far-UV (FUV) imaging to map recent star formation on longer timescales, on the order of 100Myr. We used the Ultraviolet Imaging Telescope UVIT on board Astrosat to image the galaxies of the Dorado backbone previously observed in H{alpha}+[NII], with the far-UV filter FUV.CaF2 (1300-1800{AA}). The sample included NGC 1536, NGC 1546, NGC 1549, [CMI2001]4136-01, NGC 1553, IC 2058, PGC 75125, NGC 1566, NGC 1596, and NGC 1602; for the two latter galaxies, the UVIT data provided the first view in far-UV. For the others, previously observed by GALEX, the UVIT data afford a ~5x improvement in spatial resolution. FUV.CaF2 emission is revealed in all the Dorado galaxies observed, tracing young stellar populations in ring structures and showing tidal distortions. The Sersic index, derived by fitting the luminosity profiles, is always n<3, suggesting that the FUV.CaF2 emission originates from a disk also in early-type galaxies. The star formation rate (SFR) ranges from 0.004+/-0.001M_{sun}_/yr for [CMI2001] 4136-01 to 2.455+/-0.027M_{sun}_/yr for NGC 1566. Most of the recent star formation is found at the periphery of the Dorado group, where most of late-type galaxies are located. For these galaxies, the ratio SFRH{alpha}/SFRFUV.CaF2 is close to 1, except for the edge-on IC 2058, similar to previously reported relations for local volume samples. For early-type galaxies, however, SFRH{alpha} is about 15 times higher than SFRFUV. Dorado's early-type galaxies define a separate locus in SFRFUV, SFRH{alpha} space with respect to the late-type galaxies, which is well represented by the relation log(SFRFUV.CaF2)=0.70xlog(SFRH{alpha})-1.26. The disk structure of the FUV.CaF2 emitting populations discovered in all the early-types galaxies implies dissipative processes and wet merging events. The systematic discrepancy between SFRs derived from H{alpha} and FUV fluxes suggests that rejuvenation episodes in early-type galaxies cannot sustain constant star formation over ~100Myr timescales.2022A&A...664A.192Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/664/A192CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/121/148 : Photometry of Dorado Group Dwarf Galaxies (Carrasco+, 2001)J/A+A/643/A176 : Halpha+[NII] imaging of Dorado galaxies (Rampazzo+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/664/A192https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/664/A192http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/664/A192https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/664/A192https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/664/A192http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/664/A192GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/664/A192/list (List of fits images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/664/A192/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/664/A192/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/664/A192/list?GETtext/xml+votable180.050000true64.4765417-55.93269440.0055555555555555566/33271 33954 33957-33958https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/664/A192?format=asciiUVdefaultJ/A+A/664/A192/listList of fits imagesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension of center (J2000)pos.eq.ra;meta.mainDEJ2000Declination of center (J2000)pos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintObs.dateObservation datestime.epoch;obsnullablesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitschar