2021MNRAS.501.1059R -
Mon. Not. R. Astron. Soc., 501, 1059-1071 (2021/February-2)
Low-luminosity Type II supernovae - III. SN 2018hwm, a faint event with an unusually long plateau.
REGUITTI A., PUMO M.L., MAZZALI P.A., PASTORELLO A., PIGNATA G., ELIAS-ROSA N., PRENTICE S.J., REYNOLDS T., BENETTI S., RODRIGUEZ O., MATTILA S. and KUNCARAYAKTI H.
Abstract (from CDS):
In this work, we present photometric and spectroscopic data of the low-luminosity (LL) Type IIP supernova (SN) 2018hwm. The object shows a faint (Mr = -15 mag) and very long (∼130 d) plateau, followed by a 2.7 mag drop in the r band to the radioactive tail. The first spectrum shows a blue continuum with narrow Balmer lines, while during the plateau the spectra show numerous metal lines, all with strong and narrow P-Cygni profiles. The expansion velocities are low, in the 1000-1400 km s–1 range. The nebular spectrum, dominated by H α in emission, reveals weak emission from [O I] and [Ca II] doublets. The absolute light curve and spectra at different phases are similar to those of LL SNe IIP. We estimate that 0.002 M☉ of 56Ni mass were ejected, through hydrodynamical simulations. The best fit of the model to the observed data is found for an extremely low explosion energy of 0.055 foe, a progenitor radius of 215 R☉, and a final progenitor mass of 9-10 M☉. Finally, we performed a modelling of the nebular spectrum, to establish the amount of oxygen and calcium ejected. We found a low M(16O)~0.02 M☉, but a high M(40Ca) of 0.3 M☉. The inferred low explosion energy, the low ejected 56Ni mass, and the progenitor parameters, along with peculiar features observed in the nebular spectrum, are consistent with both an electron-capture SN explosion of a superasymptotic giant branch star and with a low-energy, Ni-poor iron core-collapse SN from a 10-12 M☉ red supergiant.
Abstract Copyright:
© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
Journal keyword(s):
supernovae: general - supernovae: individual: SN 2018hwm
Errata:
erratum vol. 504, p.1162 (2021)
Simbad objects:
24
Full paper
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