Pastorello, A.Chen, T.W.Cai, Y. Z.Morales-Garoffolo, A.Cano, Z.Mason, E.Barsukova, E. A.Benetti, S.Berton, M.Bose, S.Bufano, F.Callis, E.Cannizzaro, G.Cartier, R.Chen, PingDong, SuboDyrbye, S.Elias-Rosa, N.Flörs, A.Fraser, M.Geier, S.Goranskij, V. P.Kann, D. A.Kuncarayakti, H.Onori, F.Reguitti, A.Reynolds, T.Losada, I. R.Sagués Carracedo, A.Schweyer, T.Smartt, S. J.Tatarnikov, A. M.Valeev, A. F.Vogl, C.Wevers, T.de Ugarte Postigo, A.Izzo, L.Inserra, C.Kankare, E.Maguire, K.Smith, K. W.Stalder, B.Tartaglia, L.Thöne, C. C.Valerin, G.Young, D. R.2023-04-172023-04-172019Astronomy and Astrophysics Volume 625 2019 Article number L81432-0746https://repositorio.unab.cl/xmlui/handle/ria/48634Indexación ScopusWe present the results of our photometric and spectroscopic follow-up of the intermediate-luminosity optical transient AT 2017jfs. At peak, the object reaches an absolute magnitude of Mg = -15:46 ± 0:15 mag and a bolometric luminosity of 5:5 × 1041 erg s-1. Its light curve has the doublepeak shape typical of luminous red novae (LRNe), with a narrow first peak bright in the blue bands, while the second peak is longer-lasting and more luminous in the red and near-infrared (NIR) bands. During the first peak, the spectrum shows a blue continuum with narrow emission lines of H and Fe II. During the second peak, the spectrum becomes cooler, resembling that of a K-type star, and the emission lines are replaced by a forest of narrow lines in absorption. About 5 months later, while the optical light curves are characterized by a fast linear decline, the NIR ones show a moderate rebrightening, observed until the transient disappears in solar conjunction. At these late epochs, the spectrum becomes reminiscent of that of M-type stars, with prominent molecular absorption bands. The late-time properties suggest the formation of some dust in the expanding common envelope or an IR echo from foreground pre-existing dust. We propose that the object is a common-envelope transient, possibly the outcome of a merging event in a massive binary, similar to NGC4490-2011OT1.enBinaries: CloseStars: MassiveStars: windsOutflowsSupernovaeSupernovae: Individual: AT 2017jfsSupernovae: Individual: NGC440-2011OT1ArtículoAttribution 4.0 International (CC BY 4.0)10.1051/0004-6361/201935511