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NASA Astronomers Find Planet Construction Zone Around Nearby Star


MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
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http://www.jpl.nasa.gov

Contact: Jane Platt

FOR IMMEDIATE RELEASE                        April 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
Florida, Gainesville.

       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 for life.

       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 Observatory.

       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 .

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