Interstellar dust and the sun

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An artist’s concept of the heliosphere (seen in blue, including a shocked region). The Earth is at 1 AU, and the two Voyager spacecraft are seen beyond 100 AU (the Cassini spacecraft at Saturn is also shown). A new study investigates what happens to interstellar dust that encounters the solar system and the Sun’s heliosphere. Credit: NASA and JHU/APL

The space between stars is not empty. It contains copious but diffuse amounts of gas and dust; in fact about 5-10% of the total mass of our Milky Way galaxy is in interstellar gas. About 1% of the mass of this interstellar material, quite a lot in astronomical terms, is in the form of tiny dust grains made predominantly of silicates (sand too is made of silicates), though some grains are also composed of carbon and other elements. Dust grains are important. They block visible light while emitting infrared light, and thus help determine what astronomers can see while controlling much of the energy balance in the interstellar medium (ISM) by virtue of the absorption and subsequent re-emission at longer wavelengths of light from stars. Dust is also essential to the chemistry that takes place in the ISM because it provides gas molecules with a surface on which to react with other molecules. Not least, dust contains a large fraction of many important elements in the universe like silicon, carbon, and iron. Moreover, astronomers think that at some stage in the evolution of new stars the dust around them will coagulate into large clumps—the first step towards forming planets…..
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Written by physicsgg

November 12, 2012 at 12:45 pm


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