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JET PROPULSION LABORATORY
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Contact: Jane Platt
FOR IMMEDIATE RELEASEApril 21, 1998
NASA ASTRONOMERS FIND PLANET CONSTRUCTION ZONE AROUND NEARBY STAR
NASA astronomers using the new Keck II telescope in Hawaii
have discovered what appears to be the clearest evidence yet of a
budding solar system around a nearby star.
Scientists released an image of the probable site of planet
formation around a star known as HR 4796, about 220 light-years
from Earth in the constellation Centaurus. The image, taken with
a sensitive infrared camera developed at NASA's Jet Propulsion
Laboratory, shows a swirling disc of dust around the star.
Within the disc is a telltale empty region that may have been
swept clean when material was pulled into newly formed planetary
bodies, the scientists said.
"This may be what our solar system looked like at the end of
its main planetary formation phase," said Dr. Michael Werner of
JPL, who co-discovered the region, along with Drs. David Koerner
and Michael Ressler, also of JPL, and Dana Backman of Franklin
and Marshall College, Lancaster, PA. "Comets may be forming
right now in the disc's outer portion from remaining debris."
The discovery was made on March 16 from the giant 10-meter
(33-foot) Keck II telescope atop Mauna Kea, Hawaii. Keck II and
its 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, developed by Ressler at JPL and designed to
measure heat radiation.
The four scientists reported their discovery in a submission
to Astrophysical Journal Letters. The disc was discovered
independently and contemporaneously at the Cerro Tololo
Observatory in Chile by another team of scientists, led by Ray
Jayawardhana of the Harvard-Smithsonian Center for Astrophysics,
Cambridge, MA, and Dr. Charles Telesco of the University of
Koerner of JPL said the finding represents a "missing link"
in the study of how planetary systems are born and evolve. "In a
sense, we've already peeked into the stellar family album and
seen baby pictures and middle-aged photos," Koerner said. "With
HR 4796, we're seeing a picture of a young adult star starting
its own family of planets. This is the link between discs around
very young stars and discs around mature stars, many with planets
already orbiting them."
"This is the first infrared image where an entire inner
planetary disc is clearly visible," Werner said. "The planet-
forming disc around the star Beta Pictoris was discovered in 1983
by the Infrared Astronomical Satellite (IRAS), and also later
imaged with the Hubble Space Telescope, but glaring light from
the star partially obscured its disc."
The apparent diameter of the dust disc around HR 4796 is
about 200 astronomical units (one astronomical unit is the
distance from Earth to the Sun). The diameter of the cleared
inner region is about 100 astronomical units, slightly larger
than our own solar system.
HR 4796 was originally identified as an interesting object
for further study by Dr. Michael Jura, an astronomy professor at
the University of California, Los Angeles. 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.
The discovery of the HR 4796 disc was made in just one hour
of observing time at Keck, but the JPL team plans to return to
Hawaii in June for further studies. They hope to learn more
about the structure, composition and size of this disc, and to
determine how discs around stars in our galaxy produce planets.
They plan to study several other stars as well, including Vega,
which was featured prominently in the movie, "Contact."
The Harvard/Florida research team that also found the HR
4796 disc included Drs. Lee Hartmann and Giovanni Fazio of
Harvard-Smithsonian Center for Astrophysics, and Scott Fisher and
Dr. Robert Pina of the University of Florida.
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
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, the California Institute of
Technology and NASA. Use of the Keck Observatory for Origins
research is managed by JPL for NASA's Office of Space Science,
Washington, DC. JPL is a division of Caltech.
The research of both teams was supported in large part by
the NASA Origins Program, with additional support to the
Harvard/Florida team from the National Science Foundation, the
National Optical Astronomy Observatories, and the Smithsonian
Institution; and with additional NASA support for the
Caltech/JPL-Franklin & Marshall team, including use of the Keck
The Keck II image of HR 4796 is available on the web at
http://www.jpl.nasa.gov/releases/98/hr4796.html . The image and
information on the MIRLIN camera is available at
http://cougar.jpl.nasa.gov/mirlin.html . A false-color image of
the HR 4796 disc is available at http://www.astro.ufl.edu/news/
. Information on the Keck Observatory is available at
http://www2.keck.hawaii.edu:3636 . Information on the Origins
program is available at: http://origins.jpl.nasa.gov .