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Construction Zone At a Nearby Star

HR 4796
NASA astronomers using the new "Keck II" telescope in Hawaii have discovered what seems to be the clearest evidence yet of a budding solar system developing around a nearby star.

The star, known as HR 4796, is 220 light-years from Earth in the constellation Centaurus. The astronomers are showing an image of the probable site of a planet adjacent to that star.

The picture, snapped with a sensitive infrared camera built at NASA's Jet Propulsion Laboratory (JPL) at Pasadena, California, shows a swirling disk of dust around the star. Within the disk is a telltale empty region that may have been swept clean when material was pulled into newly formed planetary bodies.

Looking back in time. The astronomers suggest the image may be what our Solar System where we live looked like at the end of its main planetary formation phase. They say comets could be forming from remaining debris right now in that faraway disk's outer portion.

They discovered the planet construction zone on March 16, 1998, with the giant 33-foot (10-meter) Keck II telescope atop Mauna Keam in Hawaii. Keck II and its older twin, Keck I, are the world's largest optical and infrared telescopes. Attached to the Keck II for this observation was the mid-infrared camera built at JPL to measure heat radiation. The disk was discovered at about the same time at the Cerro Tololo Observatory in Chile by another team of scientists.

Missing link. The NASA astronomers call their finding a "missing link" in the study of how planetary systems are born and evolve. They described the experience as something like looking into a family album and seeing baby pictures and middle-aged photos. HR 4796 is a picture of a young adult star starting its own family of planets.

The new photo is the first infrared image where an entire inner planetary disk is clearly visible. A planet-forming disk around the star Beta Pictoris was discovered in 1983 by astronomers using the Infrared Astronomical Satellite (IRAS). Later, it was imaged with the Hubble Space Telescope, but glaring light from the star partially obscured its disk.

Astronomical units. The apparent diameter of the dust disk around HR 4796 is about 200 astronomical units -- one AU is the distance from the Earth to the Sun. The diameter of the cleared inner region is about 100 AUs which is slightly larger than our own Solar System.

The star HR 4796 is about 10 million years old and is difficult to see in the continental United States, but is visible to telescopes in Hawaii and the southern hemisphere. Vega, which was featured prominently in the movie, "Contact."

The W. M. Keck Observatory is owned and operated by the California Association for Research in Astronomy, a joint venture between the University of California, California Institute of Technology (Caltech) at Pasadena, and NASA. JPL is a division of Caltech. JPL's use of the Keck telescope is supported by NASA's Origins program, a series of missions to study the formation of galaxies, stars, planets and life, and to search for Earth-like planets around other stars that might have the right conditions for life. Use of the Keck Observatory for Origins research is managed by JPL for NASA's Office of Space Science, Washington, DC.

For more information:
Introduction to Planet Hunting
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