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The material was identified on the basis of its carbon isotopic composition, which is different from the carbon found on Earth and in other parts of the Solar System. Isotopes are variations of elements that differ from each other in the number of neutrons they have, making them similar chemically but different physically.
Christine Floss, senior research scientist in Earth and Planetary Sciences and Physics at Washington University ,St. Louis, USA, said that the organic material in the IDP she and her colleagues analysed was probably formed in molecular clouds in the interstellar medium before the formation of the Solar System.
"Our findings are proof that there is pre-solar organic material coming into the Solar System today," Floss said. "This material has been preserved for more than 4.5 billion years, which is the age of the Solar System. It's amazing that it has survived for so long, a lot of IDPs will come from comets" Floss said. "It makes sense that organic material would be preserved in a very cold environment, such as where comets form at the edge of the Solar System. For something to stay this pristine and primitive, one can assume that it came from that kind of environment."
The finding help to understand the Solar System's formation and the origin of organic matter on Earth. Over the past 20 years, researchers have found isotopic anomalies in nitrogen and hydrogen from IDPs but never before in carbon. One of the expected reasons for this was the limitations of earlier instruments, using a new type of ion microprobe called the NanoSIMS, enabled researchers to analyse particles at much greater spatial resolution and higher sensitivity than before. The NanoSIMS can resolve particles as small as 100 nanometers in diameter. A hundred thousand such particles side-by-side would make a centimetre. Typically IDPs range from 100 nanometers to 500 nanometers.
Floss said it's estimated that, over a million years, about a centimetre of carbonaceous material comes in the form of cosmic dust and a significant amount of that material may be pre-solar in origin.
The work was published in the 27 February 2004 issue of Science, and was supported by NASA grants.
More info: Washington University in St. Louis
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