Supernova gravitational collapse

At the other extreme, the neutrinos and gamma rays emitted by a supernova in 1987 brought brilliant confirmation of the most elaborate theoretical speculations concerning the mechanisms of stellar explosion and the gravitational collapse which immediately precedes it. 

A scenario imagined by Zwicky in 1938 was for a long time the only explanation of the phenomenon. According to this view, a supernova marks the transformation of a normal star into a neutron star, drawing its energy from gravitational collapse. This led astronomers to think that the death of a star was the transition from luminous perfection to a kind of dark perfection. 

Apart from these three facts, nuclear astrophysicists take pains to point out that the rate at which the luminosities of SNla events decline, once beyond the maximum, is commensurable with the decay of radioactive cobalt-56, son of nickel-56, atomic nucleus of noble lineage as we know. This is a common factor with gravitational collapse supernovas. SNla light curves are explained through the hypothesis that half a solar mass of nickel-56 is produced when one of these white dwarfs explodes. 

However, the entombment of iron is only perpetrated by gravitational-collapse supernovas. Their thermonuclear counterparts are more liberal and, one might say, more final, for they leave behind no corpse, no bones, and no scrap iron. They owe this propensity for total destraction to the rigidity and fragility of the exploding body, the white dwarf, a porcelain ornament that is sure to break when it falls. But thermonuclear supernovas, though lavish providers of iron, are rare. Very special conditions must be fulfilled for these explosions to occur. 

The sightings of simultaneous, bunches of neutrinos in the KII [6] and IMB [7] detectors some three or four hours before optical observations of SN1987a is surely as good a demonstration of the existence of gravitational collapse supernovae as we can desire. The very short time between neutrinos and optical visibility is a surprise, speaking to the small size and unusual nature of the progenitor. We have performed [5] one of the many parallel analyses of these neutrinos [23-28]. 

A The instantaneous gravitational collapse of a massive star resulted in this supernova explosion observed in 1987. 

Well, our Sun takes about 30 million years to incubate as a protostar and form a mature sun. Stars three times the mass of our Sun might take just a million years to be born, and stars one tenth the size of our Sun might emerge in about 100 million years. Protostars are just dense clouds of gas and dust. Remember, a supernova triggers their gravitational collapse into a star (figures 7.2 and 7.3). 

Gravitational collapse of the core of the massive star under its own gravity leads to a supernova explosion. These are extremely energetic explosions where the observable energy in the kinetic energy of the exploded debris and electromagnetic radiation add up to several times 1051 erg. The actual energy... 

Supernova An endpoint of stellar evolution for the most massive stars, an explosion triggered by the gravitational collapse of the stellar core following the exhaustion of fuel for nuclear burning. The collapsed stellar core, depending on its final mass, can become either a black hole or a neutron star (and some of the latter may be observable as pulsars). 

A fundamental role played by molecules in the interstellar medium is as one of the cooling catalysts for the star formation process. Molecular clouds that exceed the maximum stable mass for a cloud with only thermal support, known as the Jeans mass (see Section Al), are predicted to gravitationally collapse. In order for this collapse to proceed, molecules and dust are required to radiate away energy released by the gravitational collapse. Many of the stars formed will eventually produce novae and supernovae, which further eiuich the interstellar medium with molecules that can be used as catalysts to future star formation events. 

The term supernovae describes very different explosive processes in astronomy. There are essentially two object classes that provide an observable display that is rather similar. One is the core-collapse in a massive star where the freed gravitational energy is turned into radiation in many different ways. The rich variety of core-collapse supemovae is due to the many evolutionary chan-... 

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