Related papers: SN 1999ga: a low-luminosity linear type II superno…

Many Type IIb supernovae (SNe) show a prominent additional early peak in their light curves, which is generally thought to be due to the shock cooling of extended hydrogen-rich material surrounding the helium core of the exploding star. The…

The main progenitor candidate of Type Ia supernovae (SNe Ia) is white dwarfs in binary systems where the companion star is another white dwarf (double degenerate system) or a less evolved non-degenerate star with R* >~ 0.1 Rsun (single…

Type Ia supernovae are exploding stars that are used to measure the accelerated expansion of the Universe and are responsible for most of the iron ever produced. Although there is general agreement that the exploding star is a white dwarf…

With an extinction-corrected V-band peak absolute magnitude of about -22, supernova (SN) 2006gy is probably the brightest SN ever observed. We report on multi-wavelength observations of this SN and its environment. Our spectroscopy shows an…

Supernovae of Type IIn (narrow line) appear to be explosions that had strong mass loss before the event, so that the optical luminosity is powered by the circumstellar interaction. If the mass loss region has an optical depth $>c/v_s$,…

We present extensive ugrizYHJK photometry and optical spectroscopy of SN 2005gj obtained by the SDSS-II and CSP Supernova Projects, which give excellent coverage during the first 150 days after the time of explosion. These data show that SN…

We report Nearby Supernova Factory observations of SN 2005gj, the second confirmed case of a "hybrid" Type Ia/IIn supernova. Our early-phase photometry of SN 2005gj shows that the interaction is much stronger than for the prototype, SN…

The diversity of Type II supernovae (SNe II) is thought to be driven mainly by differences in their progenitor's hydrogen-rich (H-rich) envelope mass, with SNe IIP having long plateaus ($\sim100$ days) and the most massive H-rich envelopes.…

The nature of the peculiar `Ca-rich' SN 2019ehk in the nearby galaxy M100 remains unclear. Its origin has been debated as either a stripped core-collapse supernova or a thermonuclear helium detonation event. Here, we present very late-time…

We present multiband optical photometric and spectroscopic observations of an unusual Type II supernova, SN 2018hfm, which exploded in the nearby (d = 34.67 Mpc) dwarf galaxy PGC 1297331 with a very low star-formation rate (0.0270 M yr-1)…

Supernova (SN) 1987A was a peculiar H-rich event with a long-rising (LR) light curve (LC), stemming from a compact blue supergiant star (BSG). Only a few similar events have been presented in the literature. We present new data for a sample…

Supernova 2002ic was an atypical Type Ia supernova (SN Ia) with evidence for substantial amounts of hydrogen associated with the system. Contrary to previous claims, we show that its unusual properties can be understood within the framework…

We present the discovery of a red supergiant star that exploded as supernova 2003gd in the nearby spiral galaxy M74. The Hubble Space Telescope (HST) and the Gemini Telescope imaged this galaxy 6 to 9 months before the supernova explosion…

Type IIn supernovae occur when stellar explosions are surrounded by dense hydrogen-rich circumstellar matter. The dense circumstellar matter is likely formed by extreme mass loss from their progenitors shortly before they explode. The…

For typical models of binary statistics, 50-70% of core-collapse supernova (ccSN) progenitors are members of a stellar binary at the time of the explosion. Independent of any consequences of mass transfer, this has observational…

We present our analysis of the Type II supernova DLT16am (SN~2016ija). The object was discovered during the ongoing $\rm{D}<40\,\rm{Mpc}$ (DLT40) one day cadence supernova search at $r\sim20.1\,\rm{mag}$ in the `edge-on' nearby…

We present UBVRIJHK photometry and optical spectroscopy of the so-called 'peculiar' Type Ia supernova 1999by in NGC 2841. The observations began one week before visual maximum light which is well-defined by daily observations. The light…

One method of discriminating between the many Type Ia progenitor scenarios is by searching for contaminating hydrogen and helium stripped from the companion star. We present several high-resolution 2-D numerical simulations of the impact of…

We present spectroscopic and photometric observations of the peculiar Type II supernova (SN) 1998A. The light curves and spectra closely resemble those of SN 1987A, suggesting that the SN 1998A progenitor exploded when it was a compact blue…

The progenitors of Type II-P supernovae (SNe) are generally considered to be red supergiants; however, the so-called "red supergiant problem" indicates that a deeper investigation into the progenitors of this class of SNe is necessary. SN…