Supemovae

The astrochemistty of ions may be divided into topics of interstellar clouds, stellar atmospheres, planetary atmospheres and comets. There are many areas of astrophysics (stars, planetary nebulae, novae, supemovae) where highly ionized species are important, but beyond the scope of ion chemistry . (Still, molecules, including H2O, are observed in solar spectra [155] and a surprise in the study of Supernova 1987A was the identification of molecular species, CO, SiO and possibly ITf[156. 157]. ) In the early universe, after expansion had cooled matter to the point that molecules could fonn, the small fraction of positive and negative ions that remained was crucial to the fomiation of molecules, for example [156]... 

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). 

Our planet Earth contains significant amounts of elements all the way up to Z = 92. This indicates that our solar system resulted from the gravitational collapse of a cloud of matter that included debris from second-generation stellar supemovae. Thus, our sun most likely is a third-generation star. The composition of a third-generation star includes high-Z nuclides, but the nuclear reactions are the same as those in a second-generation star. 

Burst signals (supemovae) have been the primary target for the resonant mass detectors. The minimum detectable perturbation of the metric sensor caused by a burst of GW of duration r is ... 

Ba, Nd and Sm - as well as those in C, N, A1 and Si already described - in silicon carbide. Diamonds may come from supemovae and SiC and TiC grains probably from AGB carbon stars, while the broad 12C/13C distribution in graphite suggests a variety of sources. 

Species are given with their proto-solar abundance by mass fraction, after Lodders (2003). The last column gives the yield calculated by Nomoto et al. for core-collapse supemovae within a Salpeter IMF between mass limits of 0.07 and 50 Mq. 

Further important contributions to GCE come from Type la supemovae and possibly other interacting binary systems. In the canonical SN la model, a CO white... 

Assuming the star formation rate for the Galaxy given in Table 7.9 and that all stars between 10 and 100 M explode as Type II supemovae, estimate the corresponding supernova rates for the IMFs in Table 7.8. How much difference does it make if the upper mass limit for SN is 50 M (The observed rate for SN II in galaxies like our own is of the order of 2 to 3 per century.)... 

The above models are all rather unsatisfactory, because they involve somewhat arbitrary assumptions about the time-dependence of the cosmic-ray flux and spectrum and because they predict a secondary-like behaviour for Be and B abundances, whereas the overall trend indicated by the data is more like a primary one and there are the energetic difficulties pointed out above. In the case of nB, there is a possible primary mechanism for stellar production in supemovae by neutrino spallation processes (Woosley et al. 1990 Woosley Weaver 1995), but the primary-like behaviour of beryllium in metal-poor stars, combined with a constant B/Be ratio of about 20 fully consistent with cosmic-ray spallation (Garcia Lopez et al. 1998) in the absence of any known similar process for Be, indicates that this does not solve the problem unless a primary process can be found for Be as well. Indeed,... 

Observations of distant supemovae indicate expansion of the Universe accelerating. 

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. 

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]... 

The strengths of the model are its natural connection to supemovae and star formation and that the supernova remnant would have enough time to form iron via the decay of nickel and cobalt to possibly produce the claimed iron lines. Moreover, it is expected to be a baryon-clean environment. The model is, however, very sensitive to the fine tuning of parameters. Moreover, GRB030329 places a rather strict limit of a few hours on the delay between the SN and the GRB and thus rules out the supranova model for at least this particular burst. 

Neutrino oscillations in the weak matter effect regime have been discussed extensively before [1-13], in particular, for the solar and supemovae neutrinos propagating in the matter of the Earth. The previous work has been done mainly in the approximation of constant density profile which consists of several layers with constant density. 

The fate of stars also depends on the presence of a companion. Other violent episodes known as Novae or type la supemovae result from the accretion of materials from a partner star. Supemovae of type I are thought to be responsible for most of the production of the neutron-rich isotopes of the iron group (Woosley et al. 1995 Hoflich et al. 1998). One of the key parameters in stellar evolution, and consequently the nucleosynthetic outcome, is the metallicity, defined as the proportion of elements heavier than He. 

The excess was first suggested to have a nuclear origin in stars. Almost pure O is produced in He-buming shells in massive stars, and in supemovae. On the other hand it has been shown that non-mass dependent fractionation can be produced in the laboratory by non-nuclear processes (Thiemens and Heidenreich 1983 Thiemens 1988). Similar non-linear effects have been found for O isotopes in atmospheric gases (Schueler et al. 1990 Thiemens et al. 1995). Although stellar nucleosynthesis is indeed at the origin of the O observed in the universe, the link between O isotopic anomalies in inclusions and nucleosynthesis is still under debate (Thiemens 1999 Clayton 2002). 

Besmehn A, Hoppe P (2003) A NanoSIMS study of Si- and Ca-Ti-isoptopic compositions of presolar silicon carbide grains from supemovae. Geochim Cosmochim Acta 67 4693-4703... 

Hoflich P, Wheeler JC, Thielemann FK (1998) Type la supemovae influence of the initial composition on the nucleosynthesis, light curve, and spectra and consequences for the determination of 2 and A. Astrophys 1495 617-629... 

Rauscher T, Heger A, Hoffman RD, Woosley SE (2002) Nucleosynthesis in massive stars with improved nuclear and stellar physics. Astrophys J 576 323-348 Rayet M (1995) The p-process in type II supemovae. Astron Astrophys 298 517-532 Rayet M, Prantzos N, Amould M (1990) The p-process revisited. Astron Astrophys 227 271-281 Reedy RC, Arnold JR, Lai D (1983) Cosmic-ray record in solar system matter. Science 219 127-135 Rehkamper M, Halliday AN (1999) The precise measurement of T1 isotopic compositions by MC-ICPMS application to the analysis of geological materials and meteorites. Geochim Cosmochim Acta 63 935-944... 

Jorgensen, C, K, Heavy Elements Synthesized in Supemovae and Detected in Peculiar A-type Stars. Vol. 73, pp. 199-226. 

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