Rabu, 20 Juli 2011

"Dance Of Death" Stars Found - Can Help Prove Einstein Right

A pair of aging stars have discovered 3,000 light-years is enclosed in a "dance" of death, a marriage that ends your collision and a possible supernova, astronomers say.

The binary star system consists of two white dwarfs, the burned out soul stars like the Sun. White dwarfs are gradually spiral toward each other at breakneck speed of 370 miles (595 kilometers) a second, and they are to merge in 900,000 years.

However, astronomers hope that before the collision, the stars spinning help scientists test the general theory of relativity of Einstein, and even reveal the source of a whole class of supernovae. 

"What is so amazing that this is a pair of Earth and Neptune size exotic stars that orbit each other, only one third of the Earth-Moon distance, circle around each other every 12 minutes," says research director Warren Brown, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

"And because there is no interaction or material streaming out of them, we can have a unique stellar laboratory here to search the effects of general relativity and probe the extreme gravity."

Star System offers rare look at the gravity of space

Found the dancing stars of the extent of the white dwarf pair with a 6.5 meter telescope on Mount Hopkins as a mirror in Arizona. Astronomers have measured the relative movements of the stars, looking at the light signatures, or spectra, from the stars and the other in Eclipse.

White dwarfs have densities, only a tablespoon of roads in the area of ​​these objects weighing as much as a car.

When two such massive objects whirling around each other, they raise the space-time fabric that creates ripples like those made by a stone thrown into a pond. As these ripples called gravitational waves that are produced, the couple loses a star of its energy, causing their orbits to shrink slowly.

But the newly discovered star pair is unique in that they do not swap fabrics as they spin, allowing a "clean clock" to measure the effect of gravitational waves, said Mr Brown.

"There are many pairs of stars in the universe but interact and exchange of materials among themselves because they are so close."

That "complicates their interpretation, as they rarely see a star, except for the light from the material that comes and goes between the stars."

With a pair of non-interacting, astronomers can precisely measure the variation of the orbital period of stars in the spiral toward each other.

Astrophysics, Gijs Nelemans, Radboud University in Holland and, adding that the new white dwarf is likely to be a strong source of gravitational waves, which will soon be able to detect gravitational waves space satellite named Lisa, who may begin around 2020.

"The most exciting is that the change of orbital period, it emits gravitational waves can be effectively measured," said Neleman, who was not involved in the search for new ones.

"This means not only an indirect test of general relativity, but also to directly measure gravitational waves predicted, which has never been done before," he said.

"Such a mission should really open a new way to study the universe."

Couple found can illuminate Star Evolution, Death

The discovery could also help astronomers understand the evolution of star and death. It has long been speculated, for example, the white dwarf collisions produce Type Ia supernovae, believed to be caused when matter from a companion star is spilled on a white dwarf, lifting the mass dwarfs beyond a certain physical limit and ignite a thermonuclear explosion.

When the two stars merge, existing models found, the result can be a super-massive white dwarf, or unusually weak stellar explosion, called supernova underluminous.

"If that is the ancestor of these subclasses of the few supernovae, we expect to find these exotic pairs on the same frequency as a supernova. We'll have to wait and see what happens with our investigation," Brown responsible the study said.

Initial measurements were made in March, but now the binary system was moving almost directly behind the sun from our perspective on Earth, making the pair are currently invisible to telescopes.

As a result, Brown and his team will have to wait until autumn to measure the expected shortening of the orbital period.

"Stars of merger in less than a million years is really the blink of an eye in cosmic time scales," said Brown. "Just the fact that we found something, and it is interesting to astronomers."

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