Examinando por Autor "Mazzali P.A."
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Ítem A study in scarlet: I. Photometric properties of a sample of intermediate-luminosity red transients(EDP Sciences, 2025-03) Valerin G.; Pastorello A.; Reguitti A.; Benetti S.; Cai Y.-Z.; Chen T.-W.; Eappachen D.; Elias-Rosa N.; Fraser M.; Gangopadhyay A.; Hsiao E.Y.; Howell D.A.; Inserra C.; Izzo L.; Jencson J.; Kankare E.; Kotak R.; Mazzali P.A.; Misra K.; Pignata G.; Prentice S.J.; Sand D.J.; Smartt S.J.; Stritzinger M.D.; Tartaglia L.; Valenti S.; Anderson J.P.; Andrews J.E.; Amaro R.C.; Brennan S.; Bufano F.; Callis E.; Cappellaro E.; Dastidar R.; Della Valle M.; Fiore A.; Fulton M.D.; Galbany L.; Heikkilä T.; Hiramatsu D.; Karamehmetoglu E.; Kuncarayakti H.; Leloudas G.; Lundquist M.; Mccully C.; Müller-Bravo T.E.; Nicholl M.; Ochner P.; Padilla Gonzalez E.; Paraskeva E.; Pellegrino C.; Rau A.; Reichart D.E.; Reynolds T.M.; Roy R.; Salmaso I.; Singh M.; Turatto M.; Tomasella L.; Wyatt S.Aims. We investigate the photometric characteristics of a sample of intermediate-luminosity red transients (ILRTs), a class of elusive objects with peak luminosity between that of classical novae and standard supernovae. Our goal is to provide a stepping stone in the path to reveal the physical origin of such events, thanks to the analysis of the datasets collected. Methods. We present the multi-wavelength photometric follow-up of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd, and AT 2019udc. Through the analysis and modelling of their spectral energy distribution and bolometric light curves, we inferred the physical parameters associated with these transients. Results. All four objects display a single-peaked light curve which ends in a linear decline in magnitudes at late phases. A flux excess with respect to a single blackbody emission is detected in the infrared domain for three objects in our sample, a few months after maximum. This feature, commonly found in ILRTs, is interpreted as a sign of dust formation. Mid-infrared monitoring of NGC 300 2008OT-1 761 days after maximum allowed us to infer the presence of ∼10-3-10-5 M⊙ of dust, depending on the chemical composition and the grain size adopted. The late-time decline of the bolometric light curves of the considered ILRTs is shallower than expected for 56Ni decay, hence requiring an additional powering mechanism. James Webb Space Telescope observations of AT 2019abn prove that the object has faded below its progenitor luminosity in the mid-infrared domain, five years after its peak. Together with the disappearance of NGC 300 2008OT-1 in Spitzer images seven years after its discovery, this supports the terminal explosion scenario for ILRTs. With a simple semi-analytical model we tried to reproduce the observed bolometric light curves in the context of a few solar masses ejected at few 103 km s-1 and enshrouded in an optically thick circumstellar medium. © The Authors 2025.Ítem Forbidden hugs in pandemic times: IV. Panchromatic evolution of three luminous red novae(EDP Sciences, 2023-03) Pastorello A.; Valerin G.; Fraser M.; Reguitti A.; Elias-Rosa N.; Filippenko A.V.; Rojas-Bravo C.; Tartaglia L.; Reynolds T.M.; Valenti S.; Andrews J.E.; Ashall C.; Bostroem K.A.; Brink T.G.; Burke J.; Cai Y.-Z.; Cappellaro E.; Coulter D.A.; Dastidar R.; Davis K.W.; Dimitriadis G.; Fiore A.; Foley R.J.; Fugazza D.; Galbany L.; Gangopadhyay A.; Geier S.; Gutiérrez C.P.; Haislip J.; Hiramatsu D.; Holmbo S.; Howell D.A.; Hsiao E.Y.; Hung T.; Jha S.W.; Kankare E.; Karamehmetoglu E.; Kilpatrick C.D.; Kotak R.; Kouprianov V.; Kravtsov T.; Kumar S.; Li Z.-T.; Lundquist M.J.; Lundqvist P.; Matilainen K.; Mazzali P.A.; McCully C.; Misra K.; Morales-Garoffolo A.; Moran S.; Morrell N.; Newsome M.; Padilla Gonzalez E.; Pan Y.-C.; Pellegrino C.; Phillips M.M.; Pignata G.; Piro A.L.; Reichart D.E.; Rest A.; Salmaso I.; Sand D.J.; Siebert M.R.; Smartt S.J.; Smith K.W.; Srivastav S.; Stritzinger M.D.; Taggart K.; Tinyanont S.; Yan S.-Y.; Wang L.; Wang X.-F.; Williams S.C.; Wyatt S.; Zhang T.-M.; De Boer T.; Chambers K.; Gao H.; Magnier E.We present photometric and spectroscopic data on three extragalactic luminous red novae (LRNe): AT 2018bwo, AT 2021afy, and AT 2021blu. AT 2018bwo was discovered in NGC 45 (at about 6.8 Mpc) a few weeks after the outburst onset. During the monitoring period, the transient reached a peak luminosity of 1040 erg s1. AT 2021afy, hosted by UGC 10043 (49.2 Mpc), showed a double-peaked light curve, with the two peaks reaching a similar luminosity of 2.1(±0.6) - 1041 erg s1. Finally, for AT 2021blu in UGC 5829 (∼8.6 Mpc), the pre-outburst phase was well-monitored by several photometric surveys, and the object showed a slow luminosity rise before the outburst. The light curve of AT 2021blu was sampled with an unprecedented cadence until the object disappeared behind the Sun, and it was then recovered at late phases. The light curve of LRN AT 2021blu shows a double peak, with a prominent early maximum reaching a luminosity of 6.5 - 1040 erg s1, which is half of that of AT 2021afy. The spectra of AT 2021afy and AT 2021blu display the expected evolution for LRNe: a blue continuum dominated by prominent Balmer lines in emission during the first peak, and a redder continuum consistent with that of a K-type star with narrow absorption metal lines during the second, broad maximum. The spectra of AT 2018bwo are markedly different, with a very red continuum dominated by broad molecular features in absorption. As these spectra closely resemble those of LRNe after the second peak, AT 2018bwo was probably discovered at the very late evolutionary stages. This would explain its fast evolution and the spectral properties compatible with that of an M-type star. From the analysis of deep frames of the LRN sites years before the outburst, and considerations of the light curves, the quiescent progenitor systems of the three LRNe were likely massive, with primaries ranging from about 13 M for AT 2018bwo, to 141+4 M⊙ for AT 2021blu, and over 40 M for AT 2021afy. © 2023 The Authors.