SN 2019hcc: a Type II supernova displaying early O <scp>ii</scp> lines

Parrag, Eleonora; Inserra, C.; Schulze, S.; Anderson, J. P.; Chen, Ting-Wan; Leloudas, G.; Galbany, L.; Gutiérrez, C. P.; Hiramatsu, D.; Kankare, E.; Müller-Bravo, T. E.; Nicholl, M.; Pignata, G.; Cartier, R.; Gromadzki, M.; Kozyreva, Alexandra; Rau, A.; Burke, J.; Howell, D. A.; McCully, C.; Pellegrino, C.

doi:10.1093/mnras/stab2074

Cited by 5 publications

(4 citation statements)

References 143 publications

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“…K ön yv es-T óth & Vink ó 2020 ). Ho we ver, these features were observed also in the SN Ib SN 2008D (Soderberg et al 2008 ), and in the recently proposed SN subclass of SNe Icn (Gal-Yam et al 2021 ;Pastorello et al 2021 ) and in the Type-II SN 2019hcc (Parrag et al 2021 ). 15-20 d after maximum luminosity, the spectra of SLSNe I start to remarkably reproduce the behaviour of SNe Ic and SNe Ic broad lined (SNe Ic BL) at maximum luminosity (e.g.…”

supporting

confidence: 69%

Close, bright, and boxy: the superluminous SN 2018hti

Fiore

Benetti

Nicholl

et al. 2022

Monthly Notices of the Royal Astronomical Society

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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 days. 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 ∼40 M⊙ progenitor star.

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supporting

confidence: 69%

Close, bright, and boxy: the superluminous SN 2018hti

Fiore

Benetti

Nicholl

et al. 2022

Monthly Notices of the Royal Astronomical Society

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“…Könyves-Tóth & Vinkó 2020). However, these features were observed also in the SN Ib SN 2008D (Soderberg et al 2008), and in the recently-proposed SN subclass of SNe Icn (Gal-Yam et al 2021;Pastorello et al 2021) and in the type-II SN 2019hcc (Parrag et al 2021). 15-20 days after maximum luminosity, the spectra of SLSNe I start to remarkably reproduce the behaviour of SNe Ic and SNe Ic broad lined (SNe Ic BL) at maximum luminosity (e.g.…”

Section: Introductionmentioning

confidence: 63%

Close, bright and boxy: the superluminous SN 2018hti

Fiore,

Benetti,

Nicholl

et al. 2021

Preprint

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SN 2018hti was a very nearby (𝑧 = 0.0614) superluminous supernova with an exceedingly bright absolute magnitude of -22.2 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 days. 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 𝐵 p ∼ 1.3 × 10 13 G and initial period of 𝑃 spin ∼ 1.8 ms. From the nebular spectrum modelling we infer that SN 2018hti likely results from the explosion of a ∼ 40 M progenitor star.

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“…The 'w' feature created by several overlaying narrow O ii absorption lines is clearly present in the first two spectra but it is no longer visible after the maximum brightness. While this feature is common for SLSNe-I (Quimby et al 2011) it has also been seen in other SN types, for example Type Ib SN 2008d(Soderberg et al 2008, Type Ibn SN OGLE-2012-SN-006 (Pastorello et al 2015), and Type II SN 2019hcc (Parrag et al 2021). The C ii λλ5890, 6580, 7234 emission lines identified by Anderson et al (2018b) persist until ∼ 20 d post-maximum.…”

Section: Spectroscopymentioning

confidence: 82%

SN 2018bsz: A Type I superluminous supernova with aspherical circumstellar material

Pursiainen

Leloudas

Paraskeva

et al. 2022

A&A

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We present a spectroscopic analysis of the most nearby Type I superluminous supernova (SLSN-I), SN 2018bsz. The photometric evolution of SN 2018bsz has several surprising features, including an unusual pre-peak plateau and evidence for rapid formation of dust ≳ 200 d post-peak. We show here that the spectroscopic and polarimetric properties of SN 2018bsz are also unique. While its spectroscopic evolution closely resembles SLSNe-I, with early O ii absorption and C ii P-Cygni profiles followed by Ca, Mg, Fe, and other O features, a multi-component Hα profile appearing at ∼ 30 d post-maximum is the most atypical. The Hα is at first characterised by two emission components, one at ∼ +3000 km/s and a second at ∼ −7500 km/s, with a third, near-zero-velocity component appearing after a delay. The blue and central components can be described by Gaussian profiles of intermediate width (FWHM ∼ 2000 -6000 km/s), but the red component is significantly broader (FWHM ≳ 10000 km/s) and Lorentzian. The blue Hα component evolves towards a lower-velocity offset before abruptly fading at ∼ +100 d post-maximum brightness, concurrently with a light curve break. Multi-component profiles are observed in other hydrogen lines, including Paβ, and in lines of Ca ii and He i. Spectropolarimetry obtained before (10.2 d) and after (38.4 d) the appearance of the H lines shows a large shift on the Stokes Q -U plane consistent with SN 2018bsz undergoing radical changes in its projected geometry. Assuming the supernova is almost unpolarised at 10.2 d, the continuum polarisation at 38.4 d reaches P ∼ 1.8%, implying an aspherical configuration. We propose that the observed evolution of SN 2018bsz can be explained by highly aspherical, possibly disk-like, circumstellar material (CSM) with several emitting regions. After the supernova explosion, the CSM is quickly overtaken by the ejecta, but as the photosphere starts to recede, the different CSM regions re-emerge, producing the peculiar line profiles. Based on the first appearance of Hα, we can constrain the distance of the CSM to be less than ∼ 6.5 × 10 15 cm (430 AU), or even lower (≲ 87 AU) if the pre-peak plateau is related to an eruption that created the CSM. The presence of CSM has been inferred previously for other SLSNe-I, both directly and indirectly. However, it is not clear whether the rare properties of SN 2018bsz can be generalised for SLSNe-I, for example in the context of pulsational pair instability, or whether they are the result of an uncommon evolutionary path, possibly involving a binary companion.

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SN 2019hcc: a Type II supernova displaying early O ii lines

Cited by 5 publications

References 143 publications

Close, bright, and boxy: the superluminous SN 2018hti

Close, bright, and boxy: the superluminous SN 2018hti

Close, bright and boxy: the superluminous SN 2018hti

SN 2018bsz: A Type I superluminous supernova with aspherical circumstellar material

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