A1 Refereed original research article in a scientific journal
Low luminosity Type II supernovae - IV. SN 2020cxd and SN 2021aai, at the edges of the sub-luminous supernovae class
Authors: Valerin G, Pumo ML, Pastorello A, Reguitti A, Elias-Rosa N, Gútierrez CP, Kankare E, Fraser M, Mazzali PA, Howell DA, Kotak R, Galbany L, Williams SC, Cai YZ, Salmaso I, Pinter V, Müller-Bravo TE, Burke J, Gonzalez EP, Hiramatsu D, McCully C, Newsome M, Pellegrino C
Publisher: OXFORD UNIV PRESS
Publication year: 2022
Journal: Monthly Notices of the Royal Astronomical Society
Journal acronym: MON NOT R ASTRON SOC
Volume: 513
Issue: 4
First page : 4983
Last page: 4999
Number of pages: 17
ISSN: 0035-8711
eISSN: 1365-2966
DOI: https://doi.org/10.1093/mnras/stac1182
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/175455232
Photometric and spectroscopic data for two Low Luminosity Type IIP Supernovae (LL SNe IIP) 2020cxd and 2021aai are presented. SN 2020cxd was discovered 2 d after explosion at an absolute magnitude of M-r = -14.02 +/- 0.21 mag, subsequently settling on a plateau which lasts for similar to 120 d. Through the luminosity of the late light curve tail, we infer a synthesized Ni-56 mass of (1.8 +/- 0.5) x 10(-3) M-circle dot. During the early evolutionary phases, optical spectra show a blue continuum (T > 8000 K) with broad Balmer lines displaying a P Cygni profile, while at later phases, Ca II, Fe II, Sc II, and Ba II lines dominate the spectra. Hydrodynamical modelling of the observables yields R similar or equal to 575 R-circle dot for the progenitor star, with M-ej = 7.5 M-circle dot and E similar or equal to 0.097 foe emitted during the explosion. This low-energy event originating from a low-mass progenitor star is compatible with both the explosion of a red supergiant (RSG) star and with an Electron Capture Supernova arising from a super asymptotic giant branch star. SN 2021aai reaches a maximum luminosity of M-r = -16.57 +/- 0.23 mag (correcting for A(V) = 1.92 mag), at the end of its remarkably long plateau (similar to 140 d). The estimated Ni-56 mass is (1.4 +/- 0.5) x 10(-2) M-circle dot. The expansion velocities are compatible with those of other LL SNe IIP (few 10(3) km s(-1)). The physical parameters obtained through hydrodynamical modelling are R similar or equal to 575 R-circle dot, M-ej = 15.5 M-circle dot, and E = 0.4 foe. SN 2021aai is therefore interpreted as the explosion of an RSG, with properties that bridge the class of LL SNe IIP with standard SN IIP events.
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