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Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 with the use of the refurbished instruments on HST with data taken in 2004, just before the Space Telescope Imaging Spectrograph failed, we find that the Ly[alpha] and H[alpha] lines from shock emission continue to brighten, whereas their maximum velocities continue to decrease. We observe broad, blueshifted Ly[alpha], which we attribute to resonant scattering of photons emitted from hot spots on the equatorial ring. We also detect N v [lambda][lambda]1239, 1243 angstrom line emission, but only to the red of Ly[alpha]. The profiles of the N v lines differ markedly from that of Ha, suggesting that the N4+ ions are scattered and accelerated by turbulent electromagnetic fields that isotropize the ions in the collisionless shock. 10.1126/science.1192134

Supernovae are classified spectroscopically as Type I if they have no hydrogen lines in their optical spectra and Type II if they have hydrogen lines in their optical spectra. Type [...], Spectroscopic and photometric evidence indicates that Type Ia supernovae (SNe Ia) are the thermonuclear explosions of accreting white dwarfs. However, the progenitor binary systems and hydrodynamical models for SNe Ia are still controversial. The relatively uniform light curves and spectral evolution of SNe Ia have led to their use as a standard candle for determining cosmological parameters, such as the Hubble constant, the density parameter, and the cosmological constant. Recent progress includes the calibration of the absolute maximum brightness of SNe Ia with the Hubble Space Telescope, the reduction of the dispersion in the Hubble diagram through the use of the relation between the light curve shape and the maximum brightness of SNe Ia, and the discovery of many SNe Ia with high red shifts.

Supernovae are cataclysmic stellar explosions that are accompanied by bright visual displays. The designation type II is used for supernovae that have hydrogen lines in their optical spectra, and type [...], The optical and ultraviolet emission from the type II supernova SN 1987A is currently powered by the radioactive decay of titanium-44. In contrast, the emission from SN 1993J is dominated by radiation from the interaction of the supernova shock wave with a dense, stellar wind released before the explosion. The dense wind around SN 1987A was displaced by the fast wind from the compact progenitor star, and the interaction of the supernova with dense gas is now being detected at x-ray and radio wavelengths. The expected neutron stars or black holes at the centers of these supernovae are not yet significant power sources.

The recent discovery (1) by very long baseline interferometry (VLBI) of a shell-like radio structure in SN 1993J in the galaxy M81 offers the opportunity to monitor a supernova expansion [...], A sequence of images from very long baseline interferometry shows that the young radio supernova SN 1993J is expanding with circular symmetry. However, the circularly symmetric images show emission asymmetries. A scenario in which freely expanding supernova ejecta shock mostly isotropic circumstellar material is strongly favored. The sequence of images constitutes the first 'movie' of a radio supernova.

Using images from the Hubble Space Telescope and the Gemini Telescope, we confirmed the disappearance of the progenitors of two type II supernovae (SNe) and evaluated the presence of other stars associated with them. We found that the progenitor of SN 2003gd, an M-supergiant star, is no longer observed at the SN location and determined its intrinsic brightness using image subtraction techniques. The progenitor of SN 1993J, a K-supergiant star, is also no longer present, but its B-supergiant binary companion is still observed. The disappearance of the progenitors confirms that these two supernovae were produced by red supergiants.

When a massive earthquake strikes, no sane seismologist would try to trace the ramble of a passing truck amid the noise of the aftershocks. But astronomers may have pulled off [...]

The most massive stars known today can, for short periods of time, erupt, shedding amounts of mass and energy comparable to a supernova. Such an eruption does not end a [...]

Will our universe expand forever or will the current expansion come to a halt, followed by collapse to a 'big crunch'? What is the dominant form of energy in the [...]

A team of astronomers says it has found slight, previously unnoticed variations among the exploding stars called type Ia supernovae. These explosions, thought to flare up to roughly the same [...]

Supernovae of type II are explosions of massive stars consisting of concentric shells of evolved nuclear compositions (1). High levels of [sup.56]Co radioactivity produced abundant amounts of energetic Compton electrons [...], Chemistry resulting in the formation of large carbon-bearing molecules and dust in the interior of an expanding supernova was explored, and the equations governing their abundances were solved numerically. Carbon dust condenses from initially gaseous carbon and oxygen atoms because energetic electrons produced by radioactivity in the supernova cause dissociation of the carbon monoxide molecules, which would otherwise form and limit the supply of carbon atoms. The resulting free carbon atoms enable carbon dust to grow faster by carbon association than the rate at which the dust can be destroyed by oxidation. The origin of presolar micrometer-sized carbon so[ids that are found in meteorites is thereby altered.

When Supernova 1987A burst onto the cover of Time 15 years ago this week, astrophysicist Stan Woosley of the University of California, Santa Cruz, told the magazine: 'It's like Christmas. [...], With the explosion long faded, the most spectacular star in centuries is treating astronomers to a rip-roaring new light show.

In just the past few months, astronomers have glimpsed an extraordinary new picture of the universe in the glare of the cosmic flashbulbs called supernovae. Everyone from theoretical physicists to [...]

By now, even newspaper readers with a casual interest in astronomy may have heard the unsettling message delivered by distant, exploding stars called supernovae: The universe will likely expand infinitely, [...]

In the flash of stellar explosions seen halfway back to the big bang, two groups of astronomers have read clues to the future of the universe. With the orbiting Hubble [...]

Stars in other galaxies are normally far too small to be resolved at Earth, but as Marcaide et al. report on page 1475 of this issue, a sensitive array of [...]

Supernovae release intense shock waves that light up the progenitor material and create heavier elements. Studying the remnants or these supernovae allows astronomers to glimpse the structure of the progenitor [...]

Intensive scrutiny of data from distant exploding stars has not shaken the conclusion that the universe contains a large-scale repulsive force CHICAGO--Early this year, two international teams of astronomers came […]

SAN DIEGO--A stellar explosion in a galaxy 140 million light-years away might turn out to be the Rosetta stone for scientists trying to make sense of gamma ray bursts (GRBs). [...]

Supernova 1987A: A Mysterious Stranger AN extraordinarily bright energysource, located only a fraction of a light-year from the even more extraordinary cataclysm of Supernova 1987A, has left supernova watchers both [...]

Supernova 1987A: Notes from All Over As Supernova 1987A in the Large Magellanic Cloud continues on its inexorable course-- it has currently reached magnitude 3.3, with perhaps another magnitude of [...]

A Revisit to the Guest Star of A.D. 185 SECOND YEAR OF THE CHUNG-P'INGreign period, the tenth month, day kueihai (December 7, 185), a guest star appeared within Nan-men. It [...]

Gamma Rays for Christmas The long-awaited observation of gamma rays from Supernova 1987A has given astronomers their first direct observational evidence for the theory of explosive nucleosynthesis --the idea that [...]

Pulsar, Pulsar, Where Art Thou, Pulsar? It has been 2 months now since an international team of astronomers announced their detection of a furiously rotating pulsar at the heart of [...]