Purdue News

August 1, 1984 Scientists Find Clues To Early, High-Temperature Phase In Solar System ALBUQUERQUE, N.M. — Purdue University scientists, searching for clues to the history of the solar system, today presented evidence of an early high-temperature phase never recorded before during the 47th annual meeting of the Meteoritical Society. "Though we don't know what type of event it was, it would have occurred more than 4.65 billion years ago or around the time that solid objects in the solar system formed," said Michael E. Lipschutz, professor of cosmochemistry at Purdue. "Temperatures probably reached up to 1,000 degrees Celsius (1,500 - 1,800 degrees Fahrenheit)." The researchers studied trace elements in two groups of common meteorites — low-iron chondrites and high-iron chondrites — to record information on the meteorites' age, origin and experiences. "These meteorites are normally used by scientists as model-systems for how the solar system formed," said Lipschutz. "The contents suggest that an early heating event is recorded in one of these groups." Trace elements such as bismuth, tellurium and thallium can serve as excellent markers of genetic processes of events that took place before the meteorite landed on earth, he explained. "Because they are volatile, they can be particularly helpful in learning about events involving shock or heat stress." Studies of the low-iron chondrites show that meteorites having experienced a mild shock have a high-trace element concentration, while those that have suffered more severe shock have low concentrations of these elements, said Lipschutz. "But when we look at the high-iron chondrites, we see that no matter what their shock history is, the trace element concentration is low," he explained. "It appears that the high-iron meteorites never acquired the trace element concentrations that the others did. It may be that they were formed at a higher temperature or that they acquired (trace elements) briefly and lost them because they experienced an early collisional heating that drove the elements out," said the professor. Both possibilities point to evidence of a high-temperature episode that affected only this particular group of meteorites, he added. The findings also point to first-time differences in the history of the most common materials in the solar system, said Lipschutz. "We have always assumed that the most common sorts of solar system bodies, represented by these meteorites, experienced the same things in their histories, but we now see that they have not," he said. The meteorites used in the study are commonly used to provide information on how the solar system formed, said Lipschutz. "Evidence indicates that, originally, our solar system was a rotating, lens-shaped mass of primal gas and dust," said Lipschutz. "Somehow these elements condensed, formed into primitive objects, and evolved into our current solar bodies." Some meteorites, such as those used in the study, serve as important markers of these changes, he added. "They are the only objects formed at that time that have not been changed, so they act as a record of events that happened during the time the solar system was forming." The research project at Purdue is currently funded by the National Science Foundation and the National Aeronautics and Space Administration. Research findings were presented at the meeting by David Lingner, a graduate student in chemistry working under the direction of Lipschutz. Purdue News Service: (765) 494-2096; purduenews@purdue.edu