'New computer models have bolstered the case for a theory of what causes a white-dwarf supernova to occur. Under certain conditions, the massive stellar explosions happen when a white dwarf star in a binary system accretes material from its neighbor until, eventually, the big blast occurs. ORNL astrophysicists were among researchers who applied their computational and experimental support to work published in a paper by Arizona State University. The new models help explain why the white dwarf gathers the hydrogen from its companion instead of blowing off the material as it arrives. White-dwarf supernovae interest researchers because they are believed to be the stellar factories of the heavy elements such as iron, nickel and cobalt.