Friday, April 08, 2005
Stardust To Stardust
Astrophysicists at the University of Manchester studying a distant nova have found clues on how such exploding stars helped to create the elements we and our planet are made of.
The scientists were using a giant radio telescope in the New Mexico desert to study the so-called Sakurai's Object located in the Sagittarius constellation. It is the only dying star that has been seen to blast back to life in modern times.
Albert Zijlstra, astrophysics professor at Manchester, said that the exploding star disgorged a large amount of carbon gas and dust into space. "These will find their way into regions of space where new stars form, and the dust grains may become incorporated in new planets." he said. "Our results suggest this source for cosmic carbon may be far more important than previously suspected." Zijlstra said that as much as 5% of the carbon on Earth may have come from similar stellar explosions.
Most of the other elements are created during much bigger, cataclysmic events called supernovas. The cores of such stars collapse to form so-called white dwarfs, neutron stars, or black holes.
The majority of stars cool down and die when they have used up most of their hydrogen fuel by converting it into helium. For the Sun, this will happen in about 4.5 billion years. [Before that, the sun will become a red giant, 100 times larger and 2,000 times more luminous, expanding near Mars's orbit and incinerating Earth as it grows.]
But some 25% of stars will experience a brief rebirth when their helium suddenly ignites and starts fusing into carbon. After the explosive re-ignition, the star will expand to giant proportions - expelling tonnes of carbon in the process - before rapidly burning out again. Zijlstra expects that the Sakurai's Object will cool down and die sometime after 2200.
The scientists were using a giant radio telescope in the New Mexico desert to study the so-called Sakurai's Object located in the Sagittarius constellation. It is the only dying star that has been seen to blast back to life in modern times.
Albert Zijlstra, astrophysics professor at Manchester, said that the exploding star disgorged a large amount of carbon gas and dust into space. "These will find their way into regions of space where new stars form, and the dust grains may become incorporated in new planets." he said. "Our results suggest this source for cosmic carbon may be far more important than previously suspected." Zijlstra said that as much as 5% of the carbon on Earth may have come from similar stellar explosions.
Most of the other elements are created during much bigger, cataclysmic events called supernovas. The cores of such stars collapse to form so-called white dwarfs, neutron stars, or black holes.
The majority of stars cool down and die when they have used up most of their hydrogen fuel by converting it into helium. For the Sun, this will happen in about 4.5 billion years. [Before that, the sun will become a red giant, 100 times larger and 2,000 times more luminous, expanding near Mars's orbit and incinerating Earth as it grows.]
But some 25% of stars will experience a brief rebirth when their helium suddenly ignites and starts fusing into carbon. After the explosive re-ignition, the star will expand to giant proportions - expelling tonnes of carbon in the process - before rapidly burning out again. Zijlstra expects that the Sakurai's Object will cool down and die sometime after 2200.
