Supemovae explosions

A color superconducting phase is a reasonable candidate for the state of strongly interacting matter for very large quark chemical potential [16-20], Many properties of such a state have been investigated for two and three flavor QCD. In some cases these results rely heavily on perturbation theory, which is applicable for very large chemical potentials. Some initial applications to supemovae explosions and gamma ray bursts can be found in [21] and [22] respectively, see also [27], The interested reader can find a discussion of the effects of color superconductivity on the mass-radius relationship of compact stars in [45]... 

Solution. All of the gold in the universe was originally created using the r-process in the supemovae explosions. 

Following their creation in the thermonuclear processes that might be termed stellar burning , the elements heavier than Li, principally carbon, nitrogen and oxygen, are dispersed into interstellar space by stellar winds or supemovae explosions that mark the death of certain stars. The abundances of the chemical elements have been estimated (with difficulty) by a number of authors. They do vary in different regions of the cosmos [3]. The abundances in the solar system are estimated from observations on the sun and on meteorites. Those given by Cameron [4] have been... 

Dynamical models (e.g. [4, 5]) have been constructed to study the formation of these phases and their interplay. The whole pattern is dynamical, with supemovae explosions and stellar winds from massive stars creating bubbles of hot gas expanding through the diffuse medium, accompanied by large scale motions and shock waves. 

Because the path of the s process is blocked by isotopes that undergo rapid beta decay, it cannot produce neutron-rich isotopes or elements beyond Bi, the heaviest stable element. These elements can be created by the r process, which is believed to occur in cataclysmic stellar explosions such as supemovae. In the r process the neutron flux is so high that the interaction hme between nuclei and neutrons is shorter that the beta decay lifetime of the isotopes of interest. The s process chain stops at the first unstable isotope of an element because there is time for the isotope to decay, forming a new element. In the r process, the reaction rate with neutrons is shorter than beta decay times and very neutron-rich and highly unstable isotopes are created that ultimately beta decay to form stable elements. The paths of the r process are shown in Fig. 2-3. The r process can produce neutron-rich isotopes such as Xe and Xe that cannot be reached in the s process chain (Fig. 2-3). 

In the early thirties of the last century Baade and Zwicky conjectured in their studies of supernova explosions that supemovae represent a transition from ordinary stars to compact objects, whose size is an order of magnitude smaller than the size of a white dwarf. At that time it was already known that the atomic nucleus consists of neutrons and it was clear that the density of the remnant objects must be of the same order as the nuclear density. Baade and Zwicky predicted that a supernova explosions will result in objects composed of closely packed neutrons (neutron stars). Prior to the beginning of the second World War (1939) a number of theoretical works by Landau, Oppenheimer, Volkoff and Snider showed, that indeed objects could exist with sizes about 10 km and masses about a solar mass. The density in these objects is about the nuclear saturation density and they basically consist of neutrons with a small amount of protons and electrons. The studies of neutron stars were subsequently stopped most likely due to the engagement of the nuclear scientists in the development of the nuclear bomb both in the West and the East. 

Astronomers use a variety of methods to determine the distance to objects in the universe. One of the most effective is the standard candle provided by Type la supemovae. These supemovae originate in a binary star system when a white dwarf star accretes matter from its companion. When the white dwarf reaches the Chandrasekhar limit of 1.4 solar masses, a thermonuclear runaway occurs that completely disrupts the star in a cataclysmic explosion that makes the supernova as bright as an entire galaxy. Because Type la supemovae occur in stars with similar masses and because the nuclear burning affects the entire star, they all have essentially the same intrinsic brightness and their apparent brightness observed from Earth can be used to derive the distance to the supernova. 

There are several lines of evidence that nucleosynthesis takes place in stars. The compositions of the outer envelopes of evolved low- and intermediate-mass stars show enhancements of the products of nuclear reactions (hydrogen and helium burning and s-process nucleosynthesis, as defined below). The ejecta of supemovae (stellar explosions) are highly enriched in short-lived radioactive nuclides that can only have been produced either just before or during the explosion. At the other extreme, low-mass stars in globular clusters, which apparently formed shortly after the universe formed, are deficient in metals (elements heavier than hydrogen and helium) because they formed before heavy elements were synthesized. 

This article reviews the current understanding of the supernova explosions. After a brief historical introduction the two main classes of supemovae are described starting from the classification scheme currently employed. The different energy inputs for supemovae are presented. Despite their rather different energy sources supernovae from different types reach very similar luminosities. A notable exception to this are the Gamma-Ray Bursts, which are several orders of magnitude more energetic. The characteristics of each supernova type are presented. 

It was Walter Baade who made the connection between the historical supernovae and the observed emission nebulae at their positions, thus identifying the remnants of the explosions. The most prominent object is of course the Crab Nebular (Messier 1), the leftover from the supernova in 1054 Baade 1942 May all Oort 1942. With extensive observations of bright supernovae Minkowski Minkowski 1941 introduced two subclasses. Zwicky Zwicky 1965 refined the classification scheme for supemovae further. However, for several decades only two main classes were maintained until in the early eighties it became clear that at least one further subclass needs to be added. 

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-... 

Table 2 Explosive nucleosynthesis in supemovae. Similar to Table 1, but for the explosion of the star. The (A, B) notation means A is on the ingoing channel and B is on the outgoing channel. An a is same as " He, y denotes a photon, i.e., a photodisintegration reaction when on the ingoing channel, n is a neutron, /3 shows 3-decay, and...

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