Observations and Theory of Supernovae

点击翻译按钮获取中文摘要

Wheeler, J. Craig 95-28110 Dr. Wheeler will use a combination of photometry and spectroscopy, including polarimetry, to better understand the progenitor evolution, the explosion mechanism and the use of supernovae as cosmological probes. A particular topic of exploration will be Type Ic supernovae which seem to be devoid of most of their hydrogen and helium envelopes, a critical clue to their progenitor evolution. Some of these events have rather shallow light curves resembling other events like SN 1993J with rather different spectral evolution and some have steeper light curves. This may give clues to the nature of the collapse, clumping, mixing, and explosion of these events. Also to be continued is the program of supernova polarimetry, which promises critical information concerning the nature of the ejecta and of the circumstellar environment. Preliminary results are that Type Ia supernovae are unpolarized, implying a nearly spherical ejecta and very little circumstellar scattering, but that Type II, and perhaps all collapse events, have finite polarization, implying substantial asymmetries in the ejecta or circumstellar matter. Finally, the observational program includes three supernova search programs, one a visual search for nearby bright supernovae with the newly dedicated Supernova Search Telescope, one at redshifts of Z about 0.1 to determine possible galaxy evolution effects, and one deep survey at Z about 1 to constrain cosmological models. The observing program will be complemented with coordinated theoretical investigations. These will include multi-dimensional models of thermonuclear explosions, including deflagration flames and detonation structure and stability and gravitational collapse with multi-dimensional and multi-energy group neutrino transport. Also computed will be the spectral evolution of models to compare with observations. Of special interest is the spectral evolution of models that reproduce the dispersion of light curve speed, color and maximum brightness associated with Type Ia supernovae. ***