Supernova
Supernova->> STUDYING SUPERNOVAS
Chinese astronomers recorded supernovas visible from Earth as far back as ad 185. Probably the most well-known ancient supernova is the one that created the Crab Nebula in 1054. From Chinese and Japanese records, astronomers estimate that it was about 20 times as bright as any other star in the night sky. It was visible even during the day for several weeks after it first appeared.
The last time a supernova in the Milky Way galaxy became visible from Earth was October 1604. It was bright enough to be seen at night with the naked eye for more than a year. German mathematician Johannes Kepler made detailed observations of the supernova and carefully measured its position. Since then, astronomers have not seen any supernovas in the Milky Way. A number of supernovas have appeared in other galaxies, however.
One of the most important supernovas of the 20th century, and the brightest in the sky of the northern hemisphere since 1937, burst into view on March 28, 1993, in the galaxy M 81. Astronomers noticed the strange behavior of the parent star—a huge red-colored star called a red giant—before it exploded and were able to track its changes as it became a supernova.
On February 24, 1987, one of the closest supernovas in centuries occurred in the Large Magellanic Cloud, only 160,000 light-years from Earth. A light-year is a measure of distance equal to the distance that light travels in a year, or 9.5 trillion km (5.9 trillion mi). This supernova was visible from the southern hemisphere. Since this eruption, scientists have learned that its parent star may have once been a hot blue star with a mass about 20 times that of the Sun. The star probably swelled into a red giant star before it exploded.
Scientists are continually searching for and studying supernovas. Astronomers learn about the final evolutionary paths of massive stars from supernovas. In addition, supernovas give clues to the origin of the chemical elements that make up stars, planets, and even life. A supernova in a distant galaxy can even help astronomers measure the distance to the galaxy. To do this, astronomers examine the radiation emitted by the shell of material from the star’s atmosphere and use the information they gain to develop models of how wide the shell is. They then compare the width of their model to the apparent width of the shell as viewed from Earth to estimate the distance to the supernova remnant and to its parent galaxy.
Chinese astronomers recorded supernovas visible from Earth as far back as ad 185. Probably the most well-known ancient supernova is the one that created the Crab Nebula in 1054. From Chinese and Japanese records, astronomers estimate that it was about 20 times as bright as any other star in the night sky. It was visible even during the day for several weeks after it first appeared.
The last time a supernova in the Milky Way galaxy became visible from Earth was October 1604. It was bright enough to be seen at night with the naked eye for more than a year. German mathematician Johannes Kepler made detailed observations of the supernova and carefully measured its position. Since then, astronomers have not seen any supernovas in the Milky Way. A number of supernovas have appeared in other galaxies, however.
One of the most important supernovas of the 20th century, and the brightest in the sky of the northern hemisphere since 1937, burst into view on March 28, 1993, in the galaxy M 81. Astronomers noticed the strange behavior of the parent star—a huge red-colored star called a red giant—before it exploded and were able to track its changes as it became a supernova.
On February 24, 1987, one of the closest supernovas in centuries occurred in the Large Magellanic Cloud, only 160,000 light-years from Earth. A light-year is a measure of distance equal to the distance that light travels in a year, or 9.5 trillion km (5.9 trillion mi). This supernova was visible from the southern hemisphere. Since this eruption, scientists have learned that its parent star may have once been a hot blue star with a mass about 20 times that of the Sun. The star probably swelled into a red giant star before it exploded.
Scientists are continually searching for and studying supernovas. Astronomers learn about the final evolutionary paths of massive stars from supernovas. In addition, supernovas give clues to the origin of the chemical elements that make up stars, planets, and even life. A supernova in a distant galaxy can even help astronomers measure the distance to the galaxy. To do this, astronomers examine the radiation emitted by the shell of material from the star’s atmosphere and use the information they gain to develop models of how wide the shell is. They then compare the width of their model to the apparent width of the shell as viewed from Earth to estimate the distance to the supernova remnant and to its parent galaxy.
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