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SN 2016gsd: an unusually luminous and linear Type II supernova with high velocities

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DOI

  • T. M. Reynolds, University of Turku
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  • M. Fraser, University College Dublin
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  • S. Mattila, University of Turku
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  • M. Ergon, Stockholm University
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  • L. Dessart, Universidad de Chile
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  • P. Lundqvist, Stockholm University
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  • Subo Dong, Peking Univ, Peking University, Kavli Inst Astron & Astrophys
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  • N. Elias-Rosa, University of Barcelona
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  • L. Galbany, Univ Granada, University of Granada, Dept Fis Teor & Cosmos
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  • C. P. Gutierrez, Univ Southampton, University of Southampton, Dept Phys & Astron
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  • T. Kangas, Space Telescope Sci Inst, Space Telescope Science Institute
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  • E. Kankare, Univ Turku, University of Turku, Dept Phys & Astron, Tuorla Observ
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  • R. Kotak, Univ Turku, University of Turku, Dept Phys & Astron, Tuorla Observ
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  • H. Kuncarayakti, Univ Turku, University of Turku, Finnish Ctr Astron ESO FINCA
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  • A. Pastorello, INAF, University of Padua, Istituto Nazionale Astrofisica - Italy, Osservatorio Astron Padova
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  • O. Rodriguez, Millennium Inst Astrophys MAS, Universidad Andres Bello
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  • S. J. Smartt, Queens Univ Belfast, Queens University Belfast, Sch Math & Phys, Astrophys Res Ctr
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  • M. Stritzinger
  • L. Tomasella, INAF, University of Padua, Istituto Nazionale Astrofisica - Italy, Osservatorio Astron Padova
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  • Ping Chen, Peking Univ, Peking University, Kavli Inst Astron & Astrophys
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  • J. Harmanen, Univ Turku, University of Turku, Dept Phys & Astron, Tuorla Observ
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  • G. Hozzeinzadeh, Harvard-Smithsonian Center for Astrophysics
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  • D. Andrew Howell, Las Cumbres Observatory, University of California
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  • C. Inserra, Cardiff University
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  • M. Nicholl, Univ Edinburgh, University of Edinburgh, Royal Observ Edinburgh, Inst Astron
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  • M. Nielsen
  • K. Smith, Queens Univ Belfast, Queens University Belfast, Sch Math & Phys, Astrophys Res Ctr
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  • A. Somero, Univ Turku, University of Turku, Dept Phys & Astron, Tuorla Observ
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  • R. Tronsgaard, Technical University of Denmark
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  • D. R. Young, Queens Univ Belfast, Queens University Belfast, Sch Math & Phys, Astrophys Res Ctr

We present observations of the unusually luminous Type II supernova (SN) 2016gsd. With a peak absolute magnitude of V = -19.95 +/- 0.08, this object is one of the brightest Type II SNe, and lies in the gap of magnitudes between the majority of Type II SNe and the superluminous SNe. Its light curve shows little evidence of the expected drop from the optically thick phase to the radioactively powered tail. The velocities derived from the absorption in( )H alpha are also unusually high with the blue edge tracing the fastest moving gas initially at 20 000 km s(-1), and then declining approximately linearly to 15000 km s(-1) over similar to 100 d. The dwarf host galaxy of the SN indicates a low-metallicity progenitor which may also contribute to the weakness of the metal lines in its spectra. We examine SN 2016gsd with reference to similarly luminous, linear Type II SNe such as SNe 1979C and 1998S, and discuss the interpretation of its observational characteristics. We compare the observations with a model produced by the JEKYLL code and find that a massive star with a depleted and inflated hydrogen envelope struggles to reproduce the high luminosity and extreme linearity of SN 2016gsd. Instead, we suggest that the influence of interaction between the SN ejecta and circumstellar material can explain the majority of the observed properties of the SN. The high velocities and strong H alpha absorption present throughout the evolution of the SN may imply a circumstellar medium configured in an asymmetric geometry.

Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Volume493
Issue2
Pages (from-to)1761-1781
Number of pages21
ISSN0035-8711
DOIs
Publication statusPublished - Apr 2020

    Research areas

  • techniques: imaging spectroscopy, supernovae:general, supernovae: individual: SN 2016gsd, HUBBLE-SPACE-TELESCOPE, LIGHT CURVES, MASSIVE STARS, CIRCUMSTELLAR INTERACTION, INTERACTING SUPERNOVAE, RADIATIVE-TRANSFER, NOVA 1979C, LATE TIMES, X-RAY, EMISSION

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