Largest Space Molecules Found; Buckyball Mystery Solved
Long sought outside Earth, buckyballs found in star residue.
First there was Spaceballs: the Movie. Then, of course, Spaceballs: the T-shirt, Spaceballs: the Coloring Book, and Spaceballs: the Flamethrower.
Now scientists using the Spitzer Space Telescope (and possibly the Schwartz) have discovered real spaceballs, aka buckyballs, the mysterious form of pure carbon they've sought in space for some 40 years, according to a new study.
Sporting a soccer ball-like pattern, a buckyball is a molecule whose 60 carbon atoms form a stable, hollow sphere. Even at just a billionth of a meter wide, it's the largest type of molecule yet seen in space.
Buckyballs are the spherical versions of so-called fullerene carbon molecules, which were first theorized in 1970. The molecules were first spotted in a laboratory in 1985 during experiments that simulated the atmospheric conditions of carbon-rich, aging stars.
The molecules' discoverers named buckyballs after architect Buckminster Fuller, because the molecules resemble his geodesic domes (geodesic dome picture). The find-a previously unknown form of pure carbon-earned the team a Nobel Prize. (The element's two previously known pure forms are graphite and diamond.)
Buckyballs have since been found in meteorites, Earth rocks, and candle soot. Nanotechnologists have stretched them into strong, light carbon nanotubes used in bike frames and tennis rackets. And now scientists are eyeing the molecules for superconducting materials and drug delivery.
But for decades the pure carbon spheres remained elusive in one of the places they were most expected: space.
"We've been suspecting buckyballs existed in space, primarily based on the fact that these are some of the most stable and durable materials that we know on Earth," said study leader Jan Cami, an astronomer with the University of Western Ontario, Canada.
"But up to now we hadn't found evidence for them."
(Read more space news and views at National Geographic's Breaking Orbit blog.)
Largest Molecules Found in Nebula
The team finally found its evidence in a planetary nebula called Tc-1. A planetary nebula is an interstellar gas and dust cloud left behind after a sunlike star has died.
Tc-1 is remarkably hydrogen poor-a condition necessary for buckyballs but rare in our hydrogen-rich universe. Hydrogen tends to bond with carbon atoms, so an abundance of hydrogen would prevent buckyballs from forming.
The star that formed this planetary nebula shed its hydrogen envelope many thousands of years ago. But it took a recent event-the peculiar ejection of some remnant carbon-for buckyball molecules to assemble.
(Also see "Particles Larger Than Galaxies Fill the Universe?")
It also took a bit of luck for Cami and colleagues to spot them.
Spitzer detected infrared light from the molecules because their current temperature is ideal-it's been a hundred years since the star ejected carbon, and the buckyballs are now at about room temperature.
Just a century from now, Cami said, the molecules will have drifted farther from the star and become too cool for the infrared space telescope to see.
(Related:"'God Particle' May Be Five Distinct Particles, New Evidence Shows.")
Largest Molecules in Space to Advance Cosmic Knowledge
The buckyball discovery, Cami said, should advance our understanding of the chemistry of interstellar space.
Of particular interest is the problem of diffuse interstellar bands, a series of mysterious lines in the light spectra of astronomical objects.
Breaking up the light from a star, for instance, into its rainbow-like spectrum can tell scientists what kinds of chemicals exist in the star's atmosphere, based on the unique wavelengths different molecules tend to absorb.
The interstellar bands are caused by other material absorbing some light from an object before the light reaches Earth.
Scientists have hotly debated what kinds of molecules are responsible for these bands, which have become one of the greatest mysteries in cosmic spectroscopy. But buckyballs could hold the answer.
"Now that we know buckyballs exist in space," Cami said, "we may settle whether or not they are important for this problem."
Buckyball study published in the July 23 issue of the journal Science.