Close, bright and boxy: the superluminous SN 2018hti

A Fiore, S Benetti, M Nicholl, A Reguitti, E Cappellaro, S Campana, S Bose, E Paraskeva, E Berger, T M Bravo, J Burke, Y-Z Cai, T-W Chen, P Chen, R Ciolfi, S Dong, S Gomez, M Gromadzki, C P Gutiérrez, D HiramatsuG Hosseinzadeh, D A Howell, A Jerkstrand, E Kankare, A Kozyreva, K Maguire, C McCully, P Ochner, C Pellegrino, G Pignata, R S Post, N Elias-Rosa, M Shahbandeh, S Schuldt, B P Thomas, L Tomasella, J Vinkó, C Vogl, J C Wheeler, D R Young

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SN 2018hti was a very nearby (z = 0.0614) superluminous supernova with an exceedingly bright absolute magnitude of −21.7 mag in r band at maximum. The densely sampled pre-maximum light curves of SN 2018hti show a slow luminosity evolution and constrain the rise time to ∼50 rest-frame d. We fitted synthetic light curves to the photometry to infer the physical parameters of the explosion of SN 2018hti for both the magnetar and the CSM-interaction scenarios. We conclude that one of two mechanisms could be powering the luminosity of SN 2018hti; interaction with ∼10 M⊙ of circumstellar material or a magnetar with a magnetic field of Bp∼ 1.3 × 1013 G, and initial period of Pspin∼ 1.8 ms. From the nebular spectrum modelling we infer that SN 2018hti likely results from the explosion of a ${\sim}40\, \mathrm{M}_\odot$ progenitor star.
Original languageEnglish
Pages (from-to)4484-4502
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date17 Mar 2022
Publication statusPublished - May 2022


  • Space and Planetary Science
  • Astronomy and Astrophysics


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