Astronomy

The rise and fall of an extraordinary Ca-rich transient. The discovery of ATLAS19dqr/SN 2019bkc

This work presents the observations and analysis of ATLAS19dqr/SN 2019bkc, an extraordinary rapidly evolving transient event located in an isolated environment, tens of kiloparsecs from any likely host. Its light curves rise to maximum light in 5-6 d …

Sub-Chandrasekhar progenitors favoured for Type Ia supernovae: evidence from late-time spectroscopy

A non-local-thermodynamic-equilibrium level population model of the first and second ionization stages of iron, nickel, and cobalt is used to fit a sample of XShooter optical + near-infrared (NIR) spectra of Type Ia supernovae (SNe Ia). From the …

SN 2012dn from early to late times: 09dc-like supernovae reassessed

As a candidate `super-Chandrasekhar' or 09dc-like Type Ia supernova (SN Ia), SN 2012dn shares many characteristics with other members of this remarkable class of objects but lacks their extraordinary luminosity. Here, we present and discuss the most …

The evolution of luminous red nova AT 2017jfs in NGC 4470

We present the results of our photometric and spectroscopic follow-up of the intermediate-luminosity optical transient AT 2017jfs. At peak, the object reaches an absolute magnitude of Mg = -15.46 ± 0.15 mag and a bolometric luminosity of 5.5 × 1041 …

Limits on stable iron in Type Ia supernovae from near-infrared spectroscopy

We obtained optical and near infrared spectra of Type Ia supernovae (SNe Ia) at epochs ranging from 224 to 496 days after the explosion. The spectra show emission lines from forbidden transitions of singly ionised iron and cobalt atoms. We used …

Light Curves of Hydrogen-poor Superluminous Supernovae from the Palomar Transient Factory

We investigate the light-curve properties of a sample of 26 spectroscopically confirmed hydrogen-poor superluminous supernovae (SLSNe-I) in the Palomar Transient Factory survey. These events are brighter than SNe Ib/c and SNe Ic-BL, on average, by …

Nebular spectroscopy of SN 2014J: Detection of stable nickel in near-infrared spectra

We present near-infrared (NIR) spectroscopy of the nearby supernova 2014J obtained ∼450 d after explosion. We detect the [Ni II] 1.939 μm line in the spectra indicating the presence of stable 58Ni in the ejecta. The stable nickel is not centrally …