Cas A in Context
Cassiopeia A, or Cas A is the remnant of a massive star that
exploded around three hundred years ago.
The material from the explosion is rushing outward at supersonic
speeds in excess of ten million miles per hour. As this matter
crashes into gas that surrounded the former star, shock waves
analogous to awesome sonic booms heat the gas and heat the
ejected matter to temperatures in excess of fifty million
degrees Celsius. The colors in this picture show the brightness
of the X-rays, where yellow reveals the areas with the most
intense X-ray emission.
X-ray image of Cas
This is the same Chandra/ACIS image of Cas A as the picture
above, but this coloring reveals additional information. It
shows the temperature of the hot gas in the supernova remnant:
red colors correspond to temperatures below approximately 20
million degrees Celsius, and blue colors correspond to
temperatures above approximately 30 million degrees
X-ray image of Cas
Image courtesy Gordon Garmire, Penn State U & the
The study of remnants of exploded stars, or supernovas, is
essential for our understanding of the origin of life on Earth.
The cloud of gas and dust that collapsed to form the Sun, Earth
and other planets was composed mostly of hydrogen and helium,
with a small amount of heavier elements such as carbon,
nitrogen, oxygen and iron. The only place where these and other
heavy elements necessary for life are made, is deep in the
interior of a massive star. There they remain until a
catastrophic explosion spreads them throughout space.
About every fifty years in our galaxy, a massive star explodes. The shell
of matter thrown off by the supernova creates a bubble of multi-million
degree Celsius gas called a supernova remnant. Cas A is a prime example.
The hot gas will expand and produce X-rays for thousands of years.
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