What Supernovas Are and How They Work!
A supernova is the most energetic of all stellar explosions, distinctly different from a nova and considerably brighter. It is a spontaneous explosion of a star. While a smaller star may blow off mass in stellar winds or occasional flare-ups, a supernova blows off much of its mass in a single titanic outburst. This may take the star to the amazing absolute magnitude of -14 to -20, where it blazes for days with the light of an entire galaxy! At peak luminously, a supernova may have luminosity 10 billion times of that sun.
Many supernovae have been close enough to the solar system to produce temporary “new stars” that were very prominent and recorded by ancient people. The ancient Chinese called them “guest stars.” Some astronomers have suggested such an explanation for the Star of Bethlehem.
The most famous supernova was the explosion that produced the Crab nebula. It was visible in broad daylight for 23 days in July, 1054 and at night for the subsequent 6 months. It was recorded in Chinese, Japanese, and Islamic documents, and perhaps in American Indian rock art. The Crab Nebula is the expanding remnant gas shot out of a supernova. Other supernova remnants are scattered throughout our galaxy. Records indicate about 14 supernovae in our galaxy during the last 2000 years, an average of one every 140 years. Any of us might live to see a bright one.
Supernovae occur in other galaxies, too. In 1885, a supernovae in the nearby Andromeda galaxy briefly doubled that galaxy’s brightness. By 1971, some 300 supernovae had been recorded in other galaxies.
You may be wondering, “What happens inside a star to cause a supernova explosion?” Well, this is still a problem of current research. All stars try to collapse because of gravity. Small stars contract smoothly after their hydrogen fuel runs out. Moderate stars may blow off some gas when their atmospheres expand to the red giant state. But in other stars, the density becomes so great as the stars collapse that even neutrinos-which normally escape with ease-are absorbed. The dammed-up energy eventually causes an explosion that blows much of their star into interstellar space.
As a star collapses, its density increases, atoms are fused into heavier atoms, and eventually a dense state is reached where no more nuclear reactions occur among the heavy elements in the star’s interior. At this point no new heat is produced to resist the star’s inexorable tendency (big words for “natural reaction”) to shrink. Only the forces between nuclear particles counteract gravity to determine what final, dense state the star will reach. These states produce some of the most remarkable objects known in the universe: white dwarfs, neutron stars (pulsars), and black holes.
Supernovas in Space!
NASA Info!
Telescope Studies Supernovas!
Popcorn Supernovas!
Near-Earth Supernovas!
11 New Supernovas!
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