FRAGMENTS OF AN EXPLODED STAR
Three hundred years ago a star in
the constellation Cassiopeia died in a cataclysmic
explosion, a supernova. The shredded remnants of
that explosion are called Cassiopeia A, or Cas A
Cas A is the youngest supernova remnant
identified in our Milky Way galaxy. The star that
blew up was a big one, about 15 to 25 times more
massive our Sun. Massive stars like the one that
created Cas A have
short lives. They burn through their supply of fuel
in tens of millions of years, 1000 times faster
than our Sun. With their fuel exhausted, heavy stars
begin a complex chain of events that lead to the
final dramatic explosion.
The beautiful Hubble images of Cas
A are allowing astronomers to study the debris with
great clarity, seeing for the first time that the
debris is arranged into thousands of small, cooling,
knots of gas.
The image of the Cas A supernova remnant
shown here is of a section taken of the upper rim
of the remnant's expanding shell. Near the top of
the image one can make out dozens of chains of tiny
clumps. Each small clump, originally just a small
fragment of the star, is tens of times larger than
the diameter of our solar system!
The different colors highlight parts
of the debris where particular atoms are glowing.
Dark blue fragments are those richest in oxygen,
red areas are rich in sulfur.
Credit: NASA and the Hubble
Heritage Team (STScI/AURA)
Acknowledgment: Rob Fesen (Dartmouth University)