It's The First Time The Carbon Molocules Have Been Seen Outside
The Lab
Astronomers using NASA's Spitzer Space Telescope have discovered
carbon molecules, known as "buckyballs," in space for the first
time. Buckyballs are soccer-ball-shaped molecules that were first
observed in a laboratory 25 years ago.
Buckyballs NASA Image
They are named for their resemblance to architect Buckminster
Fuller's geodesic domes, which have interlocking circles on the
surface of a partial sphere. Buckyballs were thought to float
around in space, but had escaped detection until now.
"We found what are now the largest molecules known to exist in
space," said astronomer Jan Cami of the University of Western
Ontario, Canada, and the SETI Institute in Mountain View, CA. "We
are particularly excited because they have unique properties that
make them important players for all sorts of physical and chemical
processes going on in space."
Cami authored a paper about the discovery that will appear
online Thursday in the journal Science.
Buckyballs are made of 60 carbon atoms arranged in
three-dimensional, spherical structures. Their alternating patterns
of hexagons and pentagons match a typical black-and-white soccer
ball. The research team also found the more elongated relative of
buckyballs, known as C70, for the first time in space. These
molecules consist of 70 carbon atoms and are shaped more like an
oval rugby ball. Both types of molecules belong to a class known
officially as buckminsterfullerenes, or fullerenes.
The Cami team unexpectedly found the carbon balls in a planetary
nebula named Tc 1. Planetary nebulas are the remains of stars, like
the sun, that shed their outer layers of gas and dust as they age.
A compact, hot star, or white dwarf, at the center of the nebula
illuminates and heats these clouds of material that have been
shed.
Buckyball Graph
The buckyballs were found in these clouds, perhaps reflecting a
short stage in the star's life, when it sloughs off a puff of
material rich in carbon. The astronomers used Spitzer's
spectroscopy instrument to analyze infrared light from the
planetary nebula and see the spectral signatures of the buckyballs.
These molecules are approximately room temperature -- the ideal
temperature to give off distinct patterns of infrared light that
Spitzer can detect. According to Cami, Spitzer looked at the right
place at the right time. A century from now, the buckyballs might
be too cool to be detected.
The data from Spitzer were compared with data from laboratory
measurements of the same molecules and showed a perfect match.
"We did not plan for this discovery," Cami said. "But when we
saw these whopping spectral signatures, we knew immediately that we
were looking at one of the most sought-after molecules."
In 1970, Japanese professor Eiji Osawa predicted the existence
of buckyballs, but they were not observed until lab experiments in
1985. Researchers simulated conditions in the atmospheres of aging,
carbon-rich giant stars, in which chains of carbon had been
detected. Surprisingly, these experiments resulted in the formation
of large quantities of buckminsterfullerenes. The molecules have
since been found on Earth in candle soot, layers of rock and
meteorites.
Spitzer Telescope NASA Image
The study of fullerenes and their relatives has grown into a
busy field of research because of the molecules' unique strength
and exceptional chemical and physical properties. Among the
potential applications are armor, drug delivery and superconducting
technologies.
Sir Harry Kroto, who shared the 1996 Nobel Prize in chemistry
with Bob Curl and Rick Smalley for the discovery of buckyballs,
said, "This most exciting breakthrough provides convincing evidence
that the buckyball has, as I long suspected, existed since time
immemorial in the dark recesses of our galaxy."
Previous searches for buckyballs in space, in particular around
carbon-rich stars, proved unsuccessful. A promising case for their
presence in the tenuous clouds between the stars was presented 15
years ago, using observations at optical wavelengths. That finding
is awaiting confirmation from laboratory data. More recently,
another Spitzer team reported evidence for buckyballs in a
different type of object, but the spectral signatures they observed
were partly contaminated by other chemical substances.