ShareThisBy TENILLE BONOGUORE
Monday, October 30, 2006
Floating discs of debris do indeed turn into planets, and now the world finally has evidence to prove it.
Scientists analyzing data from the Hubble Space Telescope have at last confirmed the long-held belief put forward by philosopher Emmanuel Kant more than 200 years ago.
Until now, astronomers have detected more than 200 extra-solar planets and have seen many debris discs around young stars, but they have yet to observe a planet and a debris disc around the same star.
In a paper to be published in November's Astronomical Journal, an international team of astronomers led by G. Fritz Benedict and Barbara E. McArthur of the University of Texas, Austin, show for the first time that a planet is aligned with its star's circumstellar disc of dust and gas.
The first proof that planets are born from dust comes from Earth's nearest interstellar neighbor and its gas giant planet, researchers say.
The planet, detected six years ago, orbits the nearby sunlike star called Epsilon Eridani, located 10.5 light-years from Earth in the constellation Eridanus. The planet and the star's dust disc are at the same angle: 30 degrees to Earth.
The research team studied more than 1,000 Hubble observations over three years to calculate the planet's mass and its orbit by making precise measurements of the star's location as it wobbled on the sky, a technique called astrometry. The slight wobbles are caused by the gravitational tug of the unseen planet, like a small dog pulling its master on a leash.
"We basically watched three years of a nearly seven-year-long dance of the star and its invisible partner, the planet, around their orbits," Benedict said.
The planets in our solar system share a common alignment, indicating that they were created at the same time in the sun's disc. But the sun is a middle-aged star _ 4.5 billion years old _ and its debris disc dissipated long ago.
Epsilon Eridani, however, retains its disc because it is young, only 800 million years old.
The planet _ a gas giant called Epsilon Eridani b _ is the nearest planet to Earth outside our own solar system. It orbits its star every 6.9 years.
