Back when Beta Pictoris nearly had that head-on with another star, things were hairy for awhile.
The perturber (scientific terminology for a passing blob of gravity, in this case another star) pulled a long spiral arm of dust away from Beta Pictoris like a child on the run, stealing a wad of cotton candy from another. But Beta Pictoris pulled back, and the perturber let go of most of its catch, slinking off into the darkness with just a handful.
A hundred thousand years later, scientists have only an asymmetric set of dust rings around Beta Pictoris left to study. From these, they have theorized about the perturber and its actions and suspect the scenario could provide clues to why objects in the Kuiper Belt of our own solar system follow apparently odd orbits.
The stuff around the star Beta Pictoris is similar to amalgams of dust that orbit many stars, sometimes developing into planets (hence the proper name: protoplanetary disks).
But something -- perhaps this near collision with another star -- stirred the planetary nursery, leaving a series of clumps nestled in long, thin areas of dust on one side of the star.
After studying images from the Hubble Space Telescope and ground-based telescopes, researcher Paul Kalas and his colleagues used a computer model to develop the theory of the perturber. They presented their findings last week at a meeting of the American Astronomical Society.
Modeling the near-collision
The computer simulation, produced by John Larwood of Queen Mary and Westfield College in London, came up with this scenario:
A star about one-third the mass of Beta Pictoris (and far smaller than our sun) passed during a near-collision about 100,000 years ago. This perturber pulled dust particles toward it, Kalas explained in a telephone interview. A single spiral arm was pulled out of the Beta Pictoris dust disk. Eventually this arm collapsed and formed the system of asymmetric rings.
The perturber would have pulled about 10 percent of Beta Pictoris' dust out into interstellar space, Kalas said.
In our own solar system, asteroids and comets in the Kuiper Belt, beyond the orbit of Pluto, orbit the sun in a plane that is much thicker than the stable plane in which researchers expect objects ought to be orbiting. The Kuiper Belt could be a "faint remnant of what might have happened billions of years ago," Kalas said. "Maybe Beta Pictoris, in a way, resembles an early stage of formation of our solar system."
Kalas and his colleagues are now searching the sky around Beta Pictoris, looking for the perturber.
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