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♪Music♪

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Disks of debris around stars often show striking patterns...

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Like arcs

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♪rings

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♪and spirals.

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♪Do these features tell us unseen planets are stirring gas and dust in these disks?

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♪No, according to a new NASA simulation.

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♪Interactions between dust, gas and starlight let disks form these patterns on their own.

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Starlight strips electrons from dust.

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♪These electrons heat up nearby gas.

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♪The gas pressure rises, trapping more dust

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♪which then heats more gas, trapping more dust..

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♪and a cycle of growth begins.

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♪The interplay of dust and gas results in patterns like those seen in real disks.

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♪Arcs, rings and spirals can form by themselves...

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♪no planets needed.

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♪Music♪