archive: SETI [ASTRO] Astronomers Debate Diamonds In Space

SETI [ASTRO] Astronomers Debate Diamonds In Space

Larry Klaes ( )
Mon, 03 May 1999 10:34:53 -0400

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>Date: Sat, 1 May 1999 0:16:18 GMT
>From: Ron Baalke <>
>Subject: [ASTRO] Astronomers Debate Diamonds In Space
>Reply-To: Ron Baalke <>
>European Space Agency
>Press Information Note No 07-99
>Paris, France 23 April 1999
>Most chemical elements in the Universe are produced in the stars, and thus
>the stars' environments act as huge chemical factories. The European Space
>Agency's infrared space telescope, ISO, has detected, in the dust surrounding
>a star, the chemical signature of a mysterious compound made of carbon,
>whose nature is being actively debated by astronomers all over the world.
>While some say it could be a very tiny diamond, others think it is the famous
>football-shaped molecule called "fullerene" or "buckyball". If either of
>hypotheses is confirmed it will be interesting news for industry as well.
>This is not the first time the intriguing carbonaceous compound has been
>detected in space. A peculiar elite of twelve stars are known to produce it.
>The star now added by ISO to this elite is one of the best representatives
>of this exclusive family, since it emits a very strong signal of the
>Additionally ISO found a second new member of the group with weaker
>emission, and also observed with a spectral resolution never achieved before
>other already known stars in this class.
>Astronomers think these ISO results will help solve the mystery of the true
>nature of the compound. Their publication by two different groups, from
>Spain and Canada, has triggered a debate on the topic, both in astronomy
>institutes and in chemistry laboratories. At present, mixed teams of
>astrophysicists and chemists are investigating in the lab compounds
>whose chemical signature or "fingerprint" matches that detected by ISO.
>Neither diamonds nor fullerenes have ever been detected in space, but their
>presence has been predicted. Tiny diamonds of pre-solar origin -- older than
>the Solar System -- have been found in meteorites, which supports the as
>yet unconfirmed theory of their presence in interstellar space. The fullerene
>molecule, made of 60 carbon atoms linked to form a sphere (hence the name
>"buckyball"), has also been extensively searched for in space but never
>If the carbonaceous compound detected by ISO is a fullerene or a diamond,
>there will be new data on the production of these industrially interesting
>materials. Fullerenes are being investigated as "capsules" to deliver new
>pharmaceuticals to the body. Diamonds are commonly used in the electronics
>industry and for the development of new materials; if they are formed in
>the dust surrounding some stars, at relatively low temperatures and
>conditions of low pressure, companies could learn more about the ideal
>physical conditions to produce them.
>A textbook case
>The latest star in which the compound has been found is called IRAS
>16594-4656. Like the others, it's a carbon-rich star now in the process
>of dying. It has been blasting out huge amounts of material over the last
>thousand years, becoming enclosed within a shell of dust hundreds of
>times larger than the Solar System -- a structure called a "protoplanetary
>It was in this dust -- very cold and therefore invisible to non-infrared
>telescopes -- that the Spanish group using ISO's SWS and LWS spectrometers
>detected the signature of the carbonaceous compound, in the form of a broad
>emission band at the wavelength of 21 micron.
>"We searched for the compound in twenty candidate stars and only this one
>had it. It is a real textbook case, with one of the strongest emissions ever
>detected. It gets us closer to solving the mystery and will help us to
>understand how the "chemical factories" of the Universe work", says
>ESA astronomer Pedro Garcia-Lario at the ISO Data Centre in Villafranca,
>Madrid. His group published their results in the March 10 issue of the
>Astrophysical Journal.
>They favour the fullerene option. Fullerenes would get formed during
>decomposition of the solid carbon grains condensed out of the material
>emitted by the star.
>The Canadian group obtained high-resolution ISO spectra of seven other
>stars in this class, and also detected a weak emission of the carbonaceous
>compound in a new one. They present their data in the May 11 issue of the
>Astrophysical Journal Letters.
>"Diamonds, graphite, coal and fullerenes are different forms of carbon. It
>is quite possible that the 21 micron feature arises from any one of these
>forms, although not exactly like they are on Earth", says main author Sun
>Kwok, at the University of Calgary. His group detected the carbonaceous
>compound a decade ago, for the first time, with the earlier infrared
>satellite IRAS.
>Meanwhile, results from the French group led by Louis d'Hendecourt, at the
>Institut d'Astrophysique Spatiale, in Paris, are adding to the debate. They
>isolated very tiny diamonds -- a million times smaller than a millimetre
>and thus called "nanodiamonds" -- from a sample of the Orgueil meteorite,
>and then subjected them to infrared spectroscopy. The researchers conclude
>that nanodiamonds of a certain kind, defective ones in which some atoms
>of the lattice are missing, have a "chemical signature" that matches the
>one detected in the stars very closely.
>Footnote on ISO
>ESA's infrared space telescope, ISO, was put into orbit in November 1995,
>by an Ariane 44P launcher from the European Spaceport in Kourou, French
>Guiana. Its operational phase lasted till 16 May, 1998, almost a year longer
>than expected. As an unprecedented observatory for infrared astronomy,
>able to examine cool and hidden places in the Universe, ISO made nearly
>30,000 scientific observations. These are now available to the scientific
>community via the ISO Archive ( at the ISO
>Data Centre, in Villafranca, near Madrid, Spain.
>For more information, please contact:
>ESA Public Relations Division
>Tel: +33(0) Fax:+33(0)
>Martin F. Kessler, ISO Project Scientist
>ESA's Satellite Tracking Station in Villafranca (Spain)
>Tel.: + 34 91 813 1253
>Pedro Garcia-Lario (ISO Data Centre)
>Tel: +34 918131389
>Other science contact points for this Information Note:
>Sun Kwok (Dept. of Physics and Astronomy, University of Calgary, Canada)
>Tel: +1-403-220-5414
>Louis d'Hendecourt, Directeur de Recherches CNRS (Institut d'Astrophysique
> Spatiale, Orsay, France)
>Tel: +33 (0)1 69858640
>Visit the ISO websites (hi-res images available) at:
>The four ISO instruments were built by large international teams led by:
>Camera (ISOCAM) Principal Investigator
>Dr. Catherine Cesarsky, CEA, Saclay, F.
>Tel: +33.1 - 69.08.7515
>Photometer (ISOPHOT) Principal Investigator
>Prof. Dietrich Lemke, MPI Fuer Astronomie, Heidelberg, D.
>Tel: +49 6221.528.259
>Short-Wavelength Spectrometer (SWS) Principal Investigator
>Dr Thijs de Graauw, Lab. for Space Research, Groningen, NL.
>Tel: + 31.50.363.4074
>Long-Wavelength Spectrometer (LWS) Principal Investigator
>Prof. Peter Clegg, Queen Mary and Westfield College,London, UK.
>Tel: + 44.171.975.5038
>[NOTE: Illustrations supporting this release are available at