Photometric and spectroscopic analysis of the Type II SN 2020jfo with a short plateau

TL;DR

This study provides detailed photometric and spectroscopic analysis of SN 2020jfo, a Type II supernova with a short plateau, revealing its luminosity, spectral features, and progenitor characteristics through multi-epoch observations and modelling.

Contribution

It offers new insights into the properties and progenitor mass of SN 2020jfo, including its short plateau, spectral features, and nucleosynthesis, using extensive observational data and modelling techniques.

Findings

SN 2020jfo has a short 67-day plateau and a faint peak magnitude.

The nebular spectra show prominent [Ni II] emission indicating a Ni/Fe ratio above solar.

Progenitor mass estimated between 12-15 solar masses with a massive hydrogen envelope.

Abstract

We present high-cadence photometric and spectroscopic observations of SN~2020jfo in ultraviolet and optical/near-infrared bands starting from $\sim 3$ to $\sim 434$ days after the explosion, including the earliest data with the 10.4\,m GTC. SN~2020jfo is a hydrogen-rich Type II SN with a relatively short plateau duration ($67.0 \pm 0.6$ days). When compared to other Type II supernovae (SNe) of similar or shorter plateau lengths, SN~2020jfo exhibits a fainter peak absolute $V$-band magnitude ($M_V = -16.90 \pm 0.34$ mag). SN~2020jfo shows significant H$\alpha$ absorption in the plateau phase similar to that of typical SNe~II. The emission line of stable [Ni~II] $\lambda$7378, mostly seen in low-luminosity SNe~II, is very prominent in the nebular-phase spectra of SN~2020jfo. Using the relative strengths of [Ni~II] $\lambda$7378 and [Fe~II] $\lambda$7155, we derive the Ni/Fe production (abundance) ratio of 0.08--0.10, which is $\sim 1.5$ times the solar value. The progenitor mass of SN~2020jfo from nebular-phase spectral modelling and semi-analytical modelling falls in the range of 12--15\,$M_\odot$. Furthermore, semi-analytical modelling suggests a massive H envelope in the progenitor of SN~2020jfo, which is unlikely for SNe~II having short plateaus.