ExploraTour: A Peek into the Lives of the Stars

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Prof. Robert Walker, McDonnell Center for the Space Sciences, Washington University, St. Louis, MO

Where are Stars Born?

New stars are formed in vast clouds of gas and dust that occupy the space between stars.

If you're picturing a dense fog cloud, think again. Typically in a cloud with 1 gas atom per cubic centimeter, you would have to search long and hard to find a single dust grain in a volume of space the length of a football field on each side (about 10's-100 meters). And then the dust grain is only about 1/1000 of a mm across. About 4000 dust grains could fit across a sucker stick.

Not very impressive until you add up all the dust grains in the cloud that can cover tens of light years in space. A cloud extending over 1 light year on a side contains about 8 million trillion trillion trillion trillion dust grains.

The interstellar dust grain on the left, which researchers have named Florianus, was collected by a high-flying airplane in our own atmosphere.

These dust grains absorb visible light so strongly that we cannot see into the dust cloud. Infrared light can penetrate through the cloud though, giving us a glimpse of the stars being born deep within its inner regions.

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