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Interplanetary Dust in Comets Hint towards History of Planet Formation

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Published on : Jun 13, 2018

In a new development, scientists have unearthed that interplanetary dust found in comets and asteroids may have significant clues for deeper understanding of formation of our solar system. As revealed by researchers from University of Hawaii, initial solids that formed the solar system mostly included carbon, amorphous silicate, and ice.

The dust of initial solids was mostly destroyed and newer processes led to the formation of planets. The samples of pre-solar dust are mostly found in comets. Amongst interplanetary dust articles that are believed to have originated from comets, there contain tiny glass grains called GEMS. Their diameter typically ranges from tens to hundreds of nanometers, which is less than 1/100th of the thickness of human hair.

Use of Scientific Tools Reveals Composition of Interplanetary Dust

Researchers used transmission electron microscopy to create maps of element distributions. This helped reveal that the glassy grains are composed of sub grains that combine together in a different environment prior to the making of the comet body. The combined mass is encapsulated by a different type of carbon that differs from the carbon that forms a matrix holding together GEMS and other elements of cometary dust.

As the carbon that encapsulates the sub grains and the one that forms the matrix decomposes even with weak heating, it suggests that GEMS could not have been made in the hot inner solar nebula. It would instead be made in a radiation-rich, cold environment such as the pre-solar molecular cloud or outer solar nebula. The observations made by researchers suggest that exotic grains represent existing pre-solar interstellar dust. This dust formed the building blocks of stars and planets.