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We present photometric and spectroscopic observations of the Type IIn supernova SN 2019zrk (also known as ZTF 20aacbyec). The SN shows a > 100 day precursor, with a slow rise, followed by a rapid rise to M ≈ −19.2 in the r and g bands. The post-peak light-curve decline is well fit with an exponential decay with a timescale of ∼39 days, but it shows prominent undulations, with an amplitude of ∼1 mag. Both the light curve and spectra are dominated by an interaction with a dense circumstellar medium (CSM), probably from previous mass ejections. The spectra evolve from a scattering-dominated Type IIn spectrum to a spectrum with strong P-Cygni absorptions. The expansion velocity is high, ∼16 000 km s −1 , even in the last spectra. The last spectrum ∼110 days after the main eruption reveals no evidence for advanced nucleosynthesis. From analysis of the spectra and light curves, we estimate the mass-loss rate to be ∼4 × 10 −2 M ⊙ yr −1 for a CSM velocity of 100 km s −1 , and a CSM mass of 1 M ⊙ . We find strong similarities for both the precursor, general light curve, and spectral evolution with SN 2009ip and similar SNe, although SN 2019zrk displays a brighter peak magnitude. Different scenarios for the nature of the 09ip-class of SNe, based on pulsational pair instability eruptions, wave heating, and mergers, are discussed.
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SN 2021foa: the bridge between SN IIn and Ibn
ABSTRACT We present the long-term photometric and spectroscopic analysis of a transitioning SN IIn/Ibn from –10.8 d to 150.7 d post V-band maximum. SN 2021foa shows prominent He i lines comparable in strength to the H $$\alpha$$ line around peak, placing SN 2021foa between the SN IIn and SN Ibn populations. The spectral comparison shows that it resembles the SN IIn population at pre-maximum, becomes intermediate between SNe IIn/Ibn, and at post-maximum matches with SN IIn 1996al. The photometric evolution shows a precursor at –50 d and a light curve shoulder around 17 d. The peak luminosity and colour evolution of SN 2021foa are consistent with most SNe IIn and Ibn in our comparison sample. SN 2021foa shows the unique case of an SN IIn where the narrow P-Cygni in H $$\alpha$$ becomes prominent at 7.2 d. The H $$\alpha$$ profile consists of a narrow (500–1200 km s$$^{-1}$$) component, intermediate width (3000–8000 km s$$^{-1}$$) and broad component in absorption. Temporal evolution of the H $$\alpha$$ profile favours a disc-like CSM geometry. Hydrodynamical modelling of the light curve well reproduces a two-component CSM structure with different densities ($$\rho \propto$$ r$$^{-2}$$–$$\rho \propto$$ r$$^{-5}$$), mass-loss rates (10$$^{-3}$$–10$$^{-1}$$ M$$_{\odot }$$ yr$$^{-1}$$) assuming a wind velocity of 1000 km s$$^{-1}$$ and having a CSM mass of 0.18 M$$_{\odot }$$. The overall evolution indicates that SN 2021foa most likely originated from an LBV star transitioning to a WR star with the mass-loss rate increasing in the period from 5 to 0.5 yr before the explosion or it could be due to a binary interaction.
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- PAR ID:
- 10571940
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 537
- Issue:
- 3
- ISSN:
- 0035-8711
- Format(s):
- Medium: X Size: p. 2898-2917
- Size(s):
- p. 2898-2917
- Sponsoring Org:
- National Science Foundation
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