The motivations to make ultraviolet (UV) studies of supernovae (SNe) are reviewed and discussed in the light of the results obtained so far by means of IUE and HST observations. It appears that UV studies of SNe can, and do lead to fundamental results not only for our understanding of the SN phenomenon, such as the kinematics and the metallicity of the ejecta, but also for exciting new findings...

We explore consistency among different distance measures, including Supernovae Type Ia data, measurements of the Hubble parameter, and determination of the Baryon acoustic oscillation scale. We present new constraints on the cosmic transparency combining H(z) data together with the latest Supernovae Type Ia data compilation. This combination, in the context of a flat ΛCDM model, improves curren...

Over the past three decades, supernovae observations have been the primary tool used in measuring both the current expansion rate and the expansion history of the universe. Supernovae are preferred because they are the best known standard candle and they can be observed in the early and recent universe. But because they are rare and unpredictable, they are difficult to measure. In the late 1990...

We conducted an optical CCD search for supernovae in a sample of 142 bright (m(B) 16 mag), nearby (z 0:03) starburst galaxies over the period 1988 December to 1991 June, to a limiting R-band magnitude of 18. Five supernovae were found, in all cases outside the host galaxy's nucleus. We determine supernova rates in the extranuclear regions to be 0:7h 2 SNU for type Ia, 0:7h 2 SNU for type Ib/c, ...

VLBI is the only technology that will allow sub-milliarcsecond resolution imaging in the near future. As such, it is the only way to image expanding supernovae in nearby galaxies. Such images potentially allow us to study the early evolution of neutron stars or black holes left behind by core-collapse supernovae, the circumstellar wind history of the supernova progenitor stars, the shock accele...

We present late-epoch optical photometry (BVRI) of seven normal/superluminous Type Ia supernovae: SN 2000E, SN 2000ce, SN 2000cx, SN 2001C, SN 2001V, SN 2001bg, SN 2001dp. The photometry of these objects was obtained using a template subtraction method to eliminate galaxy light contamination during aperture photometry. We show the optical light curves of these supernovae out to epochs of up to ...

Using the Very Large Array, we have detected radio emission from the site of SN 1970G in the Sc galaxy M101. These observations are 31 years after the supernova event, making SN 1970G the longest monitored radio supernova. With flux densities of 0.12± 0.020 mJy at 6 cm and 0.16± 0.015 mJy at 20 cm, the spectral index of −0.24 ± 0.20 appears to have flattened somewhat when compared with the prev...

As the first step in a comprehensive, comparative, direct analysis of the spectra of Type Ia supernovae (SNe Ia), we use the parameterized supernova synthetic–spectrum code, Synow, to interpret 26 spectra of the well–observed SN 1994D. Our results are consistent with the traditional view that the composition structure (element abundance fractions versus ejection velocity) is radially stratified...

A comparison of the ratio of the depths of two absorption features in the spectra of Type Ia supernovae (SNe Ia) near the time of maximum brightness with the blueshift of the deep red Si II absorption feature 10 days after maximum shows that the spectroscopic diversity of SNe Ia is multi–dimensional. There is a substantial range of blueshifts at a given value of the depth ratio. We also find th...

We show that the observed ratio NIb,c/NII of the subtypes Ib,c and II core-collapse supernovae depends on the metallicity of the host galaxy, as expected on theoretical grounds. However, the observed relation differs considerably from expectations based on non-rotating models of single stars with mass loss. We argue that the predictions of recent models with rotation offer a much better agreeme...