Large and Heavy Stars - Supernovae


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Supernovae are rare and most are hidden by interstellar dust. Astronomers have found many in other galaxies, but the last time one was seen in the Milky Way was in 1604. The largest and heaviest of these stars will end their life in a gigantic explosion called a supernova. It breaks out into space and will out shine an entire galaxy for several days. The glowing remains of these stars from hundreds and thousands of years can still be found and viewed.

One of the stellar remains of a supernova, which exploded in 1572 in Cassiopeia, is called Tycho Brahe, for Brahe who studied this supernova in detail. About 11,000 years ago a supernova exploded, now known as Vela, and whose center is approximately 1,500 light years from the Sun. Vela's material collided with space gas causing it to glow as it expanded at thousands of kilometers a second. Hydrogen gas bears the color of red and oxygen bears the color of blue. Vela's remnants can be observed through X-ray telescopes.

Supernovae can be found by astronomers using special telescopes, whereas before these types of telescopes, discovery was only through accidental means. With the use of automatic telescopes and computers, scientists can search hundreds of far away galaxies during one night. Others playing an important role in this process are dedicated amateur astronomers. From their eyes and memory, to the use of electronic cameras, or traditional photography, the amateur helps astronomers in important discoveries. The first amateur to discover a supernova was in 1957, and they are credited with over 130 more.

On February 23, 1987, in a small satellite galaxy of the Milky Way-Large Magellanic Cloud, the Earth's skies showed the brightest supernova in over four centuries. Its brightness reached 2.8 magnitude over an 85 day period. A burst of neutrinos was found from the core's collapse three hours before it began to brighten. The supernova's name is Supernova 1987A. It was the first supernova to be studied with modern day instruments.

Exploding supergiants are Type II supernovae. Even more powerful are the Type Ia supernova. The small white dwarf star will pull gas from the larger companion star. Its mass may increase to the point of losing the ability to support itself, which results in its self-destruction. Type Ia supernovae are consistent in always reaching the same brightness.

1. Editors. Secrets of the Universe. International Master Publishing: US. 1999