all the energy that our Sun will
produce over the course of its entire
10-billion-year lifetime.
 Type I supernovae are thought to
occur in binary star systems, where a
very small, very dense star known as
a white dwarf orbits around a normal
star. Under certain conditions the
white dwarf may draw in matter
from the normal star. If the white
dwarf’s mass approaches 1.4 times
that of the Sun, a point known as the
Chandrasekhar limit, the
accumulation of extra mass may
cause it suddenly and violently to
collapse.