Intermediate-luminosity red transients: Spectrophotometric properties and connection to electron-capture supernova explosions

Cai, Y. Z.Y. Z.CaiPASTORELLO, AndreaAndreaPASTORELLOFraser, M.M.FraserBOTTICELLA, Maria TeresaMaria TeresaBOTTICELLAELIAS DE LA ROSA, NANCY DEL CARMENNANCY DEL CARMENELIAS DE LA ROSAWang, L. -Z.L. -Z.WangKotak, R.R.KotakBENETTI, StefanoStefanoBENETTICAPPELLARO, EnricoEnricoCAPPELLAROTURATTO, MassimoMassimoTURATTOReguitti, A.A.ReguittiMattila, S.S.MattilaSmartt, S. J.S. J.SmarttAshall, C.C.AshallBenitez, S.S.BenitezChen, T. -W.T. -W.ChenHarutyunyan, A.A.HarutyunyanKankare, E.E.KankareLundqvist, P.P.LundqvistMazzali, P. A.P. A.MazzaliMorales-Garoffolo, A.A.Morales-GaroffoloOchner, P.P.OchnerPignata, G.G.PignataPrentice, S. J.S. J.PrenticeReynolds, T. M.T. M.ReynoldsShu, X. -W.X. -W.ShuStritzinger, M. D.M. D.StritzingerTARTAGLIA, LeonardoLeonardoTARTAGLIATerreran, G.G.TerreranTOMASELLA, LinaLinaTOMASELLAValenti, S.S.ValentiValerin, G.G.ValerinWang, G. J.G. J.WangWang, X. F.X. F.WangBORSATO, LUCALUCABORSATOCallis, E.E.CallisCannizzaro, G.G.CannizzaroChen, S.S.ChenCongiu, E.E.CongiuErgon, M.M.ErgonGalbany, L.L.GalbanyGal-Yam, A.A.Gal-YamGao, X.X.GaoGromadzki, M.M.GromadzkiHolmbo, S.S.HolmboHuang, F.F.HuangInserra, C.C.InserraItagaki, K.K.ItagakiKostrzewa-Rutkowska, Z.Z.Kostrzewa-RutkowskaMaguire, K.K.MaguireMargheim, S.S.MargheimMoran, S.S.MoranONORI, FrancescaFrancescaONORISagués Carracedo, A.A.Sagués CarracedoSmith, K. W.K. W.SmithSollerman, J.J.SollermanSomero, A.A.SomeroWang, B.B.WangYoung, D. R.D. R.Young2025-02-262025-02-2620210004-6361http://hdl.handle.net/20.500.12386/36241We present the spectroscopic and photometric study of five intermediate-luminosity red transients (ILRTs), namely AT 2010dn, AT 2012jc, AT 2013la, AT 2013lb, and AT 2018aes. They share common observational properties and belong to a family of objects similar to the prototypical ILRT SN 2008S. These events have a rise time that is less than 15 days and absolute peak magnitudes of between −11.5 and −14.5 mag. Their pseudo-bolometric light curves peak in the range 0.5-9.0 × 1040 erg s−1 and their total radiated energies are on the order of (0.3-3) × 1047 erg. After maximum brightness, the light curves show a monotonic decline or a plateau, resembling those of faint supernovae IIL or IIP, respectively. At late phases, the light curves flatten, roughly following the slope of the 56Co decay. If the late-time power source is indeed radioactive decay, these transients produce 56Ni masses on the order of 10−4 to 10−3 M⊙. The spectral energy distribution of our ILRT sample, extending from the optical to the mid-infrared (MIR) domain, reveals a clear IR excess soon after explosion and non-negligible MIR emission at very late phases. The spectra show prominent H lines in emission with a typical velocity of a few hundred km s−1, along with Ca II features. In particular, the [Ca II] λ7291,7324 doublet is visible at all times, which is a characteristic feature for this family of transients. The identified progenitor of SN 2008S, which is luminous in archival Spitzer MIR images, suggests an intermediate-mass precursor star embedded in a dusty cocoon. We propose the explosion of a super-asymptotic giant branch star forming an electron-capture supernova as a plausible explanation for these events. Lightcurves and spectra are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/654/A157">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/654/A157</A>...STAMPAenIntermediate-luminosity red transients: Spectrophotometric properties and connection to electron-capture supernova explosionsArticle10.1051/0004-6361/2021410782-s2.0-85118590351http://arxiv.org/abs/2108.05087v1https://www.aanda.org/articles/aa/full_html/2021/10/aa41078-21/aa41078-21.html2021A&A...654A.157CFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation