TARTAGLIA, LeonardoLeonardoTARTAGLIAFraser, M.M.FraserSand, D. J.D. J.SandValenti, S.S.ValentiSmartt, S. J.S. J.SmarttMcCully, C.C.McCullyAnderson, J. P.J. P.AndersonArcavi, I.I.ArcaviELIAS DE LA ROSA, NANCY DEL CARMENNANCY DEL CARMENELIAS DE LA ROSAGalbany, L.L.GalbanyGal-Yam, A.A.Gal-YamHaislip, J. B.J. B.HaislipHosseinzadeh, G.G.HosseinzadehHowell, D. A.D. A.HowellInserra, C.C.InserraJha, S. W.S. W.JhaKankare, E.E.KankareLundqvist, P.P.LundqvistMaguire, K.K.MaguireMattila, S.S.MattilaReichart, D.D.ReichartSmith, K. W.K. W.SmithSmith, M.M.SmithStritzinger, M.M.StritzingerSullivan, M.M.SullivanTaddia, F.F.TaddiaTOMASELLA, LinaLinaTOMASELLA2020-08-252020-08-2520170004-637Xhttp://hdl.handle.net/20.500.12386/26793We report initial observations and analysis on the Type IIb SN 2016gkg in the nearby galaxy NGC 613. SN 2016gkg exhibited a clear double-peaked light curve during its early evolution, as evidenced by our intensive photometric follow-up campaign. SN 2016gkg shows strong similarities with other Type IIb SNe, in particular, with respect to the He I emission features observed in both the optical and near-infrared. SN 2016gkg evolved faster than the prototypical Type IIb SN 1993J, with a decline similar to that of SN 2011dh after the first peak. The analysis of archival Hubble Space Telescope images indicate a pre-explosion source at SN 2016gkg’s position, suggesting a progenitor star with a ∼mid-F spectral type and initial mass 15{--}20 M {}<SUB>☉ </SUB>, depending on the distance modulus adopted for NGC 613. Modeling the temperature evolution within 5 {days} of explosion, we obtain a progenitor radius of ∼ 48{--}124 R {}<SUB>☉ </SUB>, smaller than that obtained from the analysis of the pre-explosion images (240{--}320 R {}<SUB>☉ </SUB>).STAMPAenArticle10.3847/2041-8213/aa5c7f2-s2.0-85013105606000401605400001https://iopscience.iop.org/article/10.3847/2041-8213/aa5c7f2017ApJ...836L..12TFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering