Related papers: SN 2008fv: the third type Ia supernova in NGC 3147

Among Type Ia supernovae (SNe~Ia) exist a class of overluminous objects whose ejecta mass is inferred to be larger than the canonical Chandrasekhar mass. We present and discuss the UV/optical photometric light curves, colors, absolute…

We present single-epoch, post-maximum spectropolarimetry of four Type Ia supernovae (SNe Ia) that span a range of spectral and photometric properties: SN 2002bf and SN 2004dt exhibit unusually high-velocity (HV) absorption lines. SN 1997dt…

I present an overview of optical observations (mostly spectra) of Type II, Ib, and Ic supernovae (SNe). SNe II are defined by the presence of hydrogen, and exhibit a very wide variety of properties. SNe II-L tend to show evidence of…

We report observations of Type Ia SN 2021hem, located in an apparently hostless environment. With a peak absolute B-band magnitude of -19.96 mag, and a lack of secondary maximum in near-infrared and i-band light curves make it resemble…

A few Type Ia supernovae (SNe Ia) have been suggested to be an explosion of a super-Chandrasekhar-mass white dwarf (WD) to account for their large luminosities, requiring a large amount of 56Ni. However, the candidate over-luminous SNe Ia…

We present and discuss the UV/optical photometric light curves and absolute magnitudes of the Type Ia supernova (SN) 2011de from the Swift Ultraviolet/Optical Telescope. We find it to be the UV brightest SN Ia yet observed--more than a…

Optical observations of the Type Ia supernova (SN Ia) 2005bl in NGC 4070, obtained from -6 to +66 d with respect to the B-band maximum, are presented. The photometric evolution is characterised by rapidly-declining light curves and red…

The acceleration of the expansion of the universe, and the need for Dark Energy, were inferred from the observations of Type Ia supernovae (SNe Ia). There is consensus that SNe Ia are thermonuclear explosions that destroy carbon-oxygen…

We have obtained early-time photometry and spectroscopy of Supernova (SN) 2013df in NGC 4414. The SN is clearly of Type IIb, with notable similarities to SN 1993J. From its luminosity at secondary maximum light, it appears that less…

The two peculiar Type Ic supernovae (SNe) 1997ef and 1997dq are shown to have very similar photometric and spectral evolution in the epochs when both SNe are observed (i.e. beyond $\sim 80$ days after the explosion). The early light curves…

SN 2006bt displays characteristics unlike those of any other known Type Ia supernova (SN Ia). We present optical light curves and spectra of SN 2006bt which demonstrate the peculiar nature of this object. SN 2006bt has broad, slowly…

Type Ia Supernova(SN Ia) are a powerful, albeit not completely understood, tool for cosmology. Gaps in our understanding of their progenitors and detailed physics can lead to systematic errors in the cosmological distances they measure. We…

Large photometric surveys with the aim of identifying many Type Ia supernovae (SNe) at moderate redshift are challenged in separating these SNe from other SN types. We are motivated to identify Type Ia SNe based only on broadband…

We present extensive photometric and spectroscopic observations of the Type Ia supernova (SN Ia) 2000cx in the S0 galaxy NGC 524, which reveal it to be peculiar. Photometrically, SN 2000cx is different from all known SNe Ia, and its light…

The properties of the highest velocity ejecta of normal Type Ia supernovae (SNe Ia) are studied via models of very early optical spectra of 6 SNe. At epochs earlier than 1 week before maximum, SNe with a rapidly evolving Si II 6355 line…

We present 65 optical spectra of the Type Ia supernova SN 2012fr, of which 33 were obtained before maximum light. At early times SN 2012fr shows clear evidence of a high-velocity feature (HVF) in the Si II 6355 line which can be cleanly…

We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e. objects with light-curve characteristics such as later primary maxima and absence of secondary peak in redder filters. This method is…

The Type Ia supernovae (SNe Ia) 2011by, hosted in NGC 3972, and 2011fe, hosted in M101, are optical "twins," having almost identical optical light-curve shapes, colours, and near-maximum-brightness spectra. However, SN 2011fe had…

Early observations of Type Ia supernovae (SNe$\,$Ia) provide essential clues for understanding the progenitor system that gave rise to the terminal thermonuclear explosion. We present exquisite observations of SN$\,$2019yvq, the second…

Observations of the peculiar type Ia SN~1991bg in NGC~4374 collected at ESO--La Silla and Asiago are presented and discussed. The broad--band light curves in the early months have a narrower peak and a luminosity decline faster than other…