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Strongest evidence yet that planets form from disks claimed
Oct. 9, 2006
Special to World Science
A new study has provided what astronomers call
the strongest evidence yet for what the philosopher Emmanuel Kant and scientists have long predicted: planets form from debris disks around stars. Artist's concept of the
Epsilon Eridani system. (Courtesy NASA, ESA, and G. Bacon
[STScI])
Kant, a German, first proposed more than two centuries
ago that planets are born from disks of dust and gas that swirl around their home stars.
Astronomers have reported detections of more than 200 extrasolar planets, and many debris disks around young stars. But they have yet to
identify a planet and disk around the same star.
In the new study, researchers using the Hubble Space Telescope and ground-based observatories
said they found such a system.
The astronomers, led by G. Fritz Benedict and Barbara
McArthur of the University of Texas, Austin, said the planet is aligned with the disk, called a circumstellar disk.
First detected six years ago, the world orbits the nearby Sun-like star Epsilon Eridani, 10.5 light-years from Earth in the direction of the constellation Eridanus. A light-year is the distance light travels in a year. The body is also the nearest known planet to us outside our solar system.
The planet’s orbit is tilted 30 degrees to Earth, the same angle at which the star’s disk is tilted, researchers said. The results are to appear in the November issue of the
Astronomical Journal. The researchers also used the Hubble observations to get a more precise estimate of the
world’s mass, which they calculated as 1.5 times that of Jupiter.
The astronomers calculated the mass and orbit of the planet, designated HD22049, by measuring 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.
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A new study has provided what astronomers call most solid evidence yet for what the philosopher Emmanuel Kant and scientists have long predicted: planets form from debris disks around stars. More than two centuries ago, Kant first proposed that planets are born from disks of dust and gas that swirl around their home stars. Astronomers have reported detections of more than 200 extrasolar planets, and many debris disks around young stars. But they have yet to find a planet and a debris disk around the same star. The new study used the Hubble Space Telescope and ground-based observatories. The astronomers, led by G. Fritz Benedict and Barbara McArthur of the University of Texas, Austin, reported the planet is aligned with the disk, called a circumstellar disk. Detected six years ago, the world orbits the nearby Sun-like star Epsilon Eridani, located 10.5 light-years from Earth in the direction of the constellation Eridanus. A light-year is the distance light travels in a year. The body is also the nearest known planet to us outside our solar system. The planet’s orbit is tilted 30 degrees to Earth, the same angle at which the star’s disk is tilted, researchers said. The results are to appear in the November issue of the Astronomical Journal. The researchers also used the Hubble observations to get a more precise estimate of the planet’s mass, which they calculated as 1.5 times that of Jupiter. The astronomers calculated the mass and orbit of the planet, designated HD22049, by measuring 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.