Browsing by Author "Schweyer, T."

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    The evolution of luminous red nova at 2017jfs in NGC4470?
    (EDP SCIENCES S A, 2019-01-01) 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, Ping; Dong, Subo; Dyrbye, 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.; Metsähovi Radio Observatory; INAF - Osservatorio Astronomico di Padova; Max Planck Institute for Extraterrestrial Physics; University of Cádiz; CSIC - Institute of Astrophysics of Andalusia; Osservatorio Astronomico di Trieste; Special Astrophysical Observatory of the Russian Academy of Sciences; Peking University; INAF - Osservatorio Astrofisico di Catania; University College Dublin; SRON Netherlands Institute for Space Research; National Optical Astronomy Observatory; Nordic Optical Telescope; CSIC; European Southern Observatory; Gran Telescopio Canarias; Lomonosov Moscow State University; University of Turku; Osservatorio Astronomico di Roma; Universidad Andrés Bello; KTH Royal Institute of Technology; Stockholm University; Queen's University Belfast; Max Planck Institute for Astrophysics; University of Cambridge; Cardiff University; University of Padova
    We 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.
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    SN 2017ens: The Metamorphosis of a Luminous Broadlined Type Ic Supernova into an SN IIn
    (2018-11-10) Chen, T. W.; Inserra, C.; Fraser, M.; Moriya, T. J.; Schady, P.; Schweyer, T.; Filippenko, A. V.; Perley, D. A.; Ruiter, A. J.; Seitenzahl, I.; Sollerman, J.; Taddia, F.; Anderson, J. P.; Foley, R. J.; Jerkstrand, A.; Ngeow, C. C.; Pan, Y. C.; Pastorello, A.; Points, S.; Smartt, S. J.; Smith, K. W.; Taubenberger, S.; Wiseman, P.; Young, D. R.; Benetti, S.; Berton, M.; Bufano, F.; Clark, P.; Valle, M. Della; Galbany, L.; Gal-Yam, A.; Gromadzki, M.; Gutiérrez, C. P.; Heinze, A.; Kankare, E.; Kilpatrick, C. D.; Kuncarayakti, H.; Leloudas, G.; Lin, Z. Y.; Maguire, K.; Mazzali, P.; McBrien, O.; Prentice, S. J.; Rau, A.; Rest, A.; Siebert, M. R.; Stalder, B.; Tonry, J. L.; Yu, P. C.; Metsähovi Radio Observatory; Max Planck Institute for Extraterrestrial Physics; University of Southampton; University College Dublin; National Astronomical Observatory of Japan; University of California, Berkeley; Liverpool John Moores University; University of New South Wales; Stockholm University; European Southern Observatory; University of California, Santa Cruz; Max Planck Institute for Astrophysics; National Central University; INAF - Osservatorio Astronomico di Padova; National Optical Astronomy Observatory; Queen's University Belfast; INAF - Osservatorio Astrofisico di Catania; Osservatorio Astronomico di Capodimonte; University of Pittsburgh; Weizmann Institute of Science; University of Warsaw; University of Hawai’i at Manoa; University of Turku; Technical University of Denmark; Space Telescope Science Institute
    We present observations of supernova (SN) 2017ens, discovered by the ATLAS survey and identified as a hot blue object through the GREAT program. The redshift z = 0.1086 implies a peak brightness of M g = -21.1 mag, placing the object within the regime of superluminous supernovae. We observe a dramatic spectral evolution, from initially being blue and featureless, to later developing features similar to those of the broadlined Type Ic SN 1998bw, and finally showing ∼2000 km s-1 wide Hα and Hβ emission. Relatively narrow Balmer emission (reminiscent of a SN IIn) is present at all times. We also detect coronal lines, indicative of a dense circumstellar medium. We constrain the progenitor wind velocity to ∼50-60 km s-1 based on P-Cygni profiles, which is far slower than those present in Wolf-Rayet stars. This may suggest that the progenitor passed through a luminous blue variable phase, or that the wind is instead from a binary companion red supergiant star. At late times we see the ∼2000 km s-1 wide Hα emission persisting at high luminosity (∼3 × 1040 erg s-1) for at least 100 day, perhaps indicative of additional mass loss at high velocities that could have been ejected by a pulsational pair instability.