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We present and discuss the optical spectro-photometric observations of the nearby (z=0.087) Type I superluminous supernova (SLSN I) SN 2017gci, whose peak K-corrected absolute magnitude reaches Mg=-21.5 mag. Its photometric and…
There is both observational and theoretical evidence that the ejecta of core-collapse supernovae (SNe) are structured. Rather than being smooth and homogeneous, the material is made of over-dense and under-dense regions of distinct…
In recent years, the viability of the pair-instability supernova (PISN) scenario for explaining superluminous supernovae has all but disappeared except for a few slowly-evolving examples. However, PISN are not predicted to be superluminous…
We present a simple and well defined prescription to compare absorption lines in supernova (SN) spectra with lists of transitions drawn from the National Institute of Standards and Technology (NIST) database. The method is designed to be…
Supernovae of type IIP are marked by the long plateau seen in their optical light curves. The plateau is believed to be the result of a recombination wave that propagates through the outflowing massive hydrogen envelope. Here, we…
Red supergiants (RSGs), which are progenitors of hydrogen-rich Type II supernovae (SNe), have been known to pulsate from both observations and theory. The pulsations can be present at core collapse and affect the resulting SN. However, SN…
Some hydrogen-rich core-collapse supernovae (type IIP SNe) exhibit evidence for a sustained energy source powering their light curves, resulting in a brighter and/or longer-lasting hydrogen-recombination plateau phase. We present a…
We examine recent evidence from the luminosity-redshift relation of Type Ia Supernovae (SNe Ia) for the $\sim 3 \sigma$ detection of a ``Hubble bubble'' -- a departure of the local value of the Hubble constant from its globally averaged…
We present a systematic study of Type II supernovae (SNe II) originating from progenitors with effective temperatures ($T_{\rm eff}$) and luminosities closely resembling red supergiants (RSGs) observed in pre-SN images and in the Galaxy.…
Engine-driven explosions with continuous energy input from the central system have been suggested for supernovae (SNe) associated with a Gamma-Ray Burst (GRB), super-luminous SNe (SLSNe), and at least a fraction of broad-lined SNe Ic (SNe…
We present the main observational features expected for GRBs that occur inside pulsar wind bubbles (PWBs). This is the most natural outcome of supranova model where initially a supernova explosion takes place, leaving a supra-massive NS,…
We present synthetic light curves and spectra from three-dimensional (3D) Monte Carlo radiative transfer simulations based on a 3D core-collapse supernova explosion model of an ultra-stripped $3.5\,\mathrm{M}_{\odot}$ progenitor. Our…
Much uncertainty surrounds the origin of super-luminous supernovae (SNe). Motivated by the discovery of the Type Ic SN2007bi, we study its proposed association with a pair-instability SN (PISN). We compute stellar-evolution models for…
Superhump amplitudes observed in dwarf novae during their superoutbursts depend on orbital inclination: the maximum amplitudes in systems with low inclinations are $A_\circ \approx 0.25$ mag., while at higher inclinations they increase from…
Due to the small amount of hydrogen (${\leq 0.1M_{\odot}}$) remaining on the surface of their progenitors, Type IIb supernovae are sensitive probes of the mass loss processes of massive stars towards the ends of their lives, including the…
An important and perhaps critical clue to the mechanism driving the explosion of massive stars as supernovae is provided by the accumulating evidence for asymmetry in the explosion. Indirect evidence comes from high pulsar velocities,…
Superluminous supernovae (SLSNe) are luminous transients that can be detected to high redshifts with upcoming optical time-domain surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). An interesting open…
Early light curves of many core-collapse supernovae (SNe) are thought to be powered by the interaction of the shock wave with optically thick extended material, either a bound envelope or preexplosion ejected circumstellar matter (CSM). We…
Supernovae (SNe), the luminous explosions of stars, were observed since antiquity, with typical peak luminosity not exceeding 1.2x10^{43} erg/s (absolute magnitude >-19.5 mag). It is only in the last dozen years that numerous examples of…
The properties of the first generation of stars and their supernova (SN) explosions remains unknown due to the lack of their actual observations. Recently many transient surveys are conducted and the feasibility of the detection of…