Kosmicka katastrofa moze zadesiti zvezde

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WASHINGTON (Reuters) -- A dust-cloaked star very much like our sun may have been the site of a cosmic catastrophe involving collisions between asteroids, comets or even planets, scientists reported on Wednesday.



Astronomers believe many stars had dust around them at an early planet-forming stage of their development, but this is an adolescent, and its dust is warm and very close to the star, about the same distance away as Earth is from the sun.

"The most likely explanation is that there were two really massive planet-sized objects -- about the size of Earth and Mars -- that collided with each other and spewed a huge amount of dust into interplanetary space," said Benjamin Zuckerman, a co-author of an article in the journal Nature.

"It must have been something really violent like that," Zuckerman said by telephone from the University of California-Los Angeles.

Our own planetary system is no stranger to such violence. Some astronomers theorize that the early Earth was struck by a Mars-sized object that generated a monster magma fountain, some of which condensed to form the moon.

But that was probably in Earth's infancy, when it was perhaps tens of millions of years old; the star in question is likely hundreds of millions of years old, still younger than Earth's estimated age of 4.5 billion years or so.

The immense amounts of dust close to the star -- known as BD+20 307 -- suggest that other planets may also be lurking, UCLA scientists said in a statement.

Because the dust is pulverized into tiny particles, scientists believe the cosmic catastrophe may have occurred within the last several thousand years, an eye blink in terms of cosmic time.

"This star is a real exception," said Zuckerman. "For something the age of this star, there's nothing comparable."

The dusty star is about 300 light-years from Earth, relatively close by cosmic standards. A light-year is about 6 trillion miles (10 trillion km), the distance light travels in a year.

It has about the same mass as our sun and is about as bright, the scientists said.

http://www.cnn.com/2005/TECH/space/07/21/space.catastrophe.reut/index.html