There may be a lot more planets out there than previously thought, according to researchers who found the makings of planetary systems around two stars orbiting each other in the constellation Taurus.
Astronomers from the National University of Mexico tuned powerful radio telescopes on the double-star system and found to their surprise that each star is encircled by a dense disk of planet-forming dust and gas. The rings contain enough material to form two sets of planets.
The dust rings are surprising because the stars are relatively close, at 4 billion miles apart. Many scientists had theorized that the gravitational tug of war between stars so close together would tear apart such rings.
"I'm sure the theorists are going to have to go back to the blackboard to see whether it makes sense that both of these stars are retaining their disks since they're so close together," said Geoffrey Marcy, who heads a four-member team of San Francisco State researchers that has discovered several planets outside the solar system.
The images of the double-star system 450 light-years from Earth were published in Thursday's issue of the journal Nature.
They are the first pictures that show discernible disks of dust and hot gas around both stars in a binary system. Each disk extends about 1 billion miles from its host star. The stars circle each other about once every 100 years.
To obtain the images, Luis Rodriguez of the National University of Mexico used the Very Large Array of the National Radio Astronomy Laboratory in New Mexico. It can detect radio wavelengths like those emitted by cosmic dust.
The findings could prompt planet-searching scientists to focus more frequently on double-star systems, which account for about 75 percent of all stars, said Robert Mathieu, a professor of astronomy at the University of Wisconsin-Madison.
"If there's this one case, there's probably plenty more out there," he said.
Of the nine planets discovered outside our solar system so far, three are in binary star systems, although those stars orbit at a greater distances than the pair Rodriguez examined, Marcy said.
If the rings discovered by Rodriguez develop into planets, a visitor to one of those far-off worlds could witness a scene similar to that in "Star Wars" where Luke Skywalker watches as two suns set on his home planet.
"If you were on one of these planets, you would see a sun in the sky and then there would be this other faint star in the sky with its own set of planets," Rodriguez said.