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News Release 130 of 297

July 28, 2005 02:00 PM (EDT)

News Release Number: STScI-2005-21

Hubble Pinpoints Doomed Star that Explodes as Supernova

July 28, 2005: Amidst the glitter of billions of stars in the majestic spiral galaxy called the Whirlpool (M51), a massive star abruptly ends its life in a brilliant flash of light. NASA's Hubble Space Telescope snapped images of the exploding star, called supernova (SN) 2005cs, 12 days after its discovery. Astronomers then compared those photos with Hubble images of the same region before the supernova blast to pinpoint the progenitor star (the star that exploded).

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Q & A: Understanding the Discovery

  1. 1. Why do some stars explode as supernovae?


  2. Two types of stars generate supernovae. The first type, called a type Ia supernova is produced by a star's burned- out core. This stellar relic, called a white dwarf, siphons hydrogen from a companion star, thereby making it 1.4 times more massive than our Sun [called the Chandrasekhar limit]. This excess bulk leads to explosive burning of carbon and other chemical elements that make up the white dwarf, thereby producing a supernova explosion.

    A star that is more than eight times as massive as our Sun generates the second type, called type II. When the star runs out of nuclear fuel, the core collapses, but when it reaches enormous densities, the collapse is halted, as if hitting a brick wall. The shock wave that ensues propagates through the outer layers and rips them apart, ejecting these layers at speeds of ten thousand miles per second.

  3. 2. What is a red supergiant star?


  4. A red supergiant is an old, bright star, much larger and cooler than the Sun. Red supergiants are about eight to 15 times more massive than the Sun. These massive stars live just a few hundred million years. The Sun's lifespan is 10 billion years.

    Betelgeuse, one of the brightest stars in the constellation Orion, is a red supergiant star. It is about 10,000 times brighter than the Sun.

 
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Photo Credit: NASA, ESA, W. Li and A. Filippenko (University of California, Berkeley), S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA)