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Space soccer balls are common

Artist's impression of buckyballs and PAHs in space

Artistic representation of buckyballs and polycyclic aromatic hydrocarbons around an R Coronae Borealis star rich in hydrogen. Image courtesy MultiMedia Service (IAC).

  • Buckyballs are large soccer ball-shaped molecules with 60 carbon atoms
  • They’ve been found on Earth, in meteorites, and now in deep space
  • Might have played a role in bringing material to Earth to kick-start life

OBSERVATIONS MADE WITH NASA’s Spitzer Space Telescope have provided surprises concerning the presence of buckminsterfullerenes, or “buckyballs,” the largest known molecules in space.

Buckyballs are made of 60 carbon atoms arranged in shape similar to a soccer ball, with patterns of alternating hexagons and pentagons. Their structure is reminiscent of Buckminster Fuller’s famous geodesic domes, for which they are named. These molecules are very stable and difficult to destroy.

A study of certain kinds of stars by David L. Lambert, Director of The University of Texas at Austin’s McDonald Observatory, and colleagues shows that buckyballs are more common in space than previously thought.

The team found that “buckyballs do not occur in very rare hydrogen-poor environments as previously thought, but in commonly found hydrogen-rich environments and, therefore, are more common in space than previously believed,” Lambert says.

Richard Curl, Harold Kroto, and Richard Smalley won the 1996 Nobel Prize in chemistry for synthesising buckyballs in a laboratory.

The consensus based on lab experiments has been that buckyballs do not form in space environments that have hydrogen, because the hydrogen would inhibit their formation.

Instead, the idea has been that stars with very little hydrogen but rich in carbon—such as the so-called R Coronae Borealis stars—provide an ideal environment for their formation in space.

Skeletal representation of a Buckyball

Skeletal representation of a Buckyball, with its obvious resemblance to a soccer ball.

Buckyballs more common than thought

Lambert, along with N. Kameswara Rao of the Indian Institute of Astrophysics and Domingo Anibal Garcia-Hernandez of the Instituto de Astrofisica de Canarias, put these theories to the test. They used the Spitzer Space Telescope to take infrared spectra of R Coronae Borealis stars to look for buckyballs in their chemical make-up.

They found these molecules do not occur in those R Coronae Borealis stars with little or no hydrogen, an observation contrary to expectation. The group also found that buckyballs do exist in the two R Coronae Borealis stars in their sample that contain a fair amount of hydrogen.

Studies published last year, including one by Garcia-Hernandez, showed that buckyballs were present in planetary nebulae rich in hydrogen.

Together, these results tell us that fullerenes are much more abundant than previously believed, because they are formed in normal and common “hydrogen-rich” and not rare “hydrogen-poor” environments.

The current observations have changed our understanding of how buckyballs form. It suggests they are created when ultraviolet radiation strikes dust grains or by collisions of gas.

The dust grains are vaporised, producing an interesting chemistry where buckyballs and polycyclic aromatic hydrocarbons (PAHs) are formed. PAHs are molecules of a variety of sizes are formed from carbon and hydrogen.

Buckyballs have been found on Earth and in meteorites, and now in space, and can act as “cages” to capture other atoms and molecules. Some theories suggest that the buckyballs may have carried to the Earth substances that make life possible.

The research will appear in the March 10 issue of The Astrophysical Journal.

Adapted from information issued by The University of Texas McDonald Observatory and the Instituto de Astrofisica de Canarias.

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Buckyballs in space!

Artist's conception of buckyballs in space

NASA's Spitzer Space Telescope has at last found buckyballs in space, as illustrated by this artist's conception showing the carbon balls coming out from the type of object where they were discovered—a dying star and the material it sheds, known as a planetary nebula. (The nebula Tc 1 does not show up well in images, so a picture of the NGC 2440 nebula, taken by the Hubble Space Telescope, was used in this artist's conception.)

  • Soccer ball-shaped molecules detected in a nebula
  • Buckyballs are collections of 60 carbon atoms
  • Spitzer Space Telescope in “right place at the right time”

How’s this for a kick-off? 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 seen in a laboratory 25 years ago.

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, California.

“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 appeared last 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.

Spotted in an ageing star system

The Cami team unexpectedly found the carbon balls in a planetary nebula (a cloud of gas) named Tc 1. Planetary nebulae are the remains of stars like the Sun, which shed their outer layers of gas and dust as they age.

A compact, hot star, or white dwarf, at the centre of the nebula illuminates and heats these clouds of material that has been shed.

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 the Spitzer Space Telescope’s spectroscopy instrument to analyse infrared light from the planetary nebula and see the spectral signatures of the buckyballs.

Spectrum of Tc 1 showing the signatures of buckyballs

Spectral data from NASA's Spitzer Space Telescope show the signatures of buckyballs in space.

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.”

Intriguing 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.

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 armour, 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.

Adapted from information issued by NASA / ESA / STScI / JPL-Caltech / University of Western Ontario.

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