NASA has announced new findings from the Spitzer Space
Telescope, including the discovery of significant amounts of
icy organic materials sprinkled throughout several “planetary
construction zones,” or dusty planet-forming discs, which
circle infant stars.
These materials, icy dust particles coated with water,
methanol and carbon dioxide, may help explain the origin of
icy planetoids like comets. Scientists believe these comets
may have endowed Earth with some of its water and many of its
biogenic, life-enabling materials.
Drs. Dan Watson and William Forrest of the University of
Rochester, N.Y, identified the ices. They surveyed five very
young stars in the constellation Taurus, 420 light-years from
Earth. Previous studies identified similar organic materials
in space, but this is the first time they were seen
unambiguously in the dust making up planet-forming discs.
In another finding, Spitzer surveyed a group of young stars
and found intriguing evidence that one of them may have the
youngest planet detected. The observatory found a clearing in
the disc around the star CoKu Tau 4. This might indicate an
orbiting planet swept away the disc material, like a vacuum
leaving a cleared trail on a dirty carpet. The new findings
reveal the structure of the gap more clearly than ever
before. Because CoKu Tau 4 is only about one million years
old, the possible planet would be even younger. As a
comparison, Earth is approximately 4.5-billion years old.
“These early results show Spitzer will dramatically expand
our understanding of how stars and planets form, which
ultimately helps us understand our origins,” said Dr. Michael
Werner, Spitzer project scientist at NASA’s Jet Propulsion
Laboratory (JPL), Pasadena, Calif., which manages the
mission.
Spitzer also discovered two of the farthest and faintest
planet-forming discs ever observed. These discs surround two
of more than 300 newborn stars uncovered for the first time
in a stunning new image of the dusty stellar nursery called
RCW 49. It is approximately 13,700 light-years from Earth in
the constellation Centaurus.
“Preliminary data suggest all 300 or more stars harbor
discs, but so far we’ve only looked closely at two. Both were
found to have discs,” said Dr. Ed Churchwell of the
University of Wisconsin, Madison, Wis., principal
investigator of the RCW 49 research, with Dr. Barbara Whitney
of Space Science Institute, Boulder, Colo.
Planet forming, “protoplanetary,” discs are a natural phase
in a star’s life. A star is born inside a dense envelope of
gas and dust. Within this envelope, and circling the star, is
a flat, dusty disc, where planets are born.
“By seeing what’s behind the dust, Spitzer has shown us star
and planet formation is a very active process in our galaxy,”
Churchwell said.
Spitzer’s exquisitely sensitive infrared eyes can see planet
forming discs in great detail. “Previously, scientists could
study only a small sample of discs, but Spitzer is already on
its way toward analyzing thousands of discs,” Werner said.
Spitzer’s infrared spectrograph instrument, which breaks
apart infrared light to see the signatures of various
chemicals, was used to observe the organic ices and the
clearing within CoKu Tau 4’s disc. Spitzer’s infrared array
camera found the new stars in RCW 49. Papers on the research
will appear in the September 1, 2004, issue of the journal
Astrophysical Journal Supplements. For images and information
about the research on the Internet, visit:
http://www.spitzer.caltech.edu
http://photojournal.jpl.nasa.gov
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