Browsing by Author "Falk, Sydney Westervelt"

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    Supernovae light curves
    (1972) Falk, Sydney Westervelt; Clayton, Donald D.
    The characteristics of the light curves of supernovae, (luminosities as functions of time) are an old problem in Astrophysics. Characteristic half-widths (in the visual spectrum) are of the order of 20 - 50 days, with peak (integrated) luminous energies at least of the order of 1050 ergs. In addition, spectroscopy reveals Doppler shifts suggesting associated velocities of expansion of the order of 103 - 104 km/sec in the outer regions of the exploding star. The problem of constructing a hydrodynamic model of such an object, which duplicates the features of the light curve, especially the energetics and the temporal characteristics, is further complicated by the presence of a variety of distinct types of supernovae, with widely varying light curves. An attempt is made to explore the hydrodynamic structure required to produce such characteristic luminosities, with emphasis upon the case of radiative diffusion as the dominant mode of energy transport. The models investigated will be of concentric spherical mass shells expanding radially at velocities of order 103 - 104 km/sec. Effects of the outer zones becoming optically thin will be examined, as well as effects of varying masses, compositions, ionization, shock wave heating, and radioactive decay of the (possible) nuclear products of the "explosion". It is hoped that the successful specification of such parameters as mass, composition, spatial size, as well as the mechanism responsible for the supernova outburst, will add to our understanding of the processes of stellar evolution, nucleosynthesis, and galactic evolution.