T. de Jaeger

SN 2011hs: A fast and faint type IIb supernova from a supergiant progenitor

Observations spanning a large wavelength range, from X-ray to radio, of the Type IIb supernova (SN) 2011hs are presented, covering its evolution during the first year after explosion. The optical light curve presents a narrower shape and a fainter luminosity at peak than previously observed for Type IIb SNe. High expansion velocities are measured from the broad absorption H I and He I lines. From the comparison of the bolometric light curve and the time evolution of the photospheric velocities with hydrodynamical models, we found that SN 2011hs is consistent with the explosion of a 3–4 M⊙ He-core progenitor star, corresponding to a main-sequence mass of 12–15 M⊙, that ejected a mass of 56Ni of about 0.04 M⊙, with an energy of E = 8.5 × 1050 ERG. Such a low-mass progenitor scenario is in full agreement with the modelling of the nebular spectrum taken at ∼215 d from maximum. From the modelling of the adiabatic cooling phase, we infer a progenitor radius of ≈500–600 R⊙, clearly pointing to an extended progenitor star. The radio light curve of SN 2011hs yields a peak luminosity similar to that of SN 1993J, but with a higher mass-loss rate and a wind density possibly more similar to that of SN 2001ig. Although no significant deviations from a smooth decline have been found in the radio light curves, we cannot rule out the presence of a binary companion star.

Nebular phase observations of the Type-Ib supernova iPTF13bvn favour a binary progenitor

Aims. We present and analyse late-time observations of the type-Ib supernova with possible pre-supernova progenitor detection, iPTF13bvn, taken at

A Hubble diagram from Type II Supernovae based solely on photometry: the Photometric-Colour Method

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Type II supernovae as probes of environment metallicity: observations of host H II regions

300 days after the explosion, and discuss these in the context of constraints on the supernovas progenitor. Previous studies have proposed two possible natures for the progenitor of the supernova, i.e. a massive Wolf-Rayet star or a lower-mass star in close binary system. Methods. Our observations show that the supernova has entered the nebular phase, with the spectrum dominated by Mg~I]

Defining Photometric Peculiar Type Ia Supernovae

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A Type II Supernova Hubble diagram from the CSP-I, SDSS-II, and SNLS surveys

4571, [O~I]

AN INDEPENDENT MEASUREMENT OF THE INCIDENCE OF Mg II ABSORBERS ALONG GAMMA-RAY BURST SIGHT LINES: THE END OF THE MYSTERY?

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SN 2016jhj at redshift 0.34: extending the Type II supernova Hubble diagram using the standard candle method

6300, 6364, and [Ca~II]

SN 2011A: A LOW-LUMINOSITY INTERACTING TRANSIENT WITH A DOUBLE PLATEAU AND STRONG SODIUM ABSORPTION

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A surge of light at the birth of a supernova

7291, 7324 emission lines. We measured the emission line fluxes to estimate the core oxygen mass and compare the [O~I]/[Ca~II] line ratio with other supernovae. Results. The core oxygen mass of the supernova progenitor was estimated to be