ScienceShot: Stardust in the Wind

On the grand scale of the cosmos, a grain of dust may seem of no consequence. But dust grains in space conglomerate to give birth to rocky planets like Earth. Now the Very Large Telescope in Chile (shown right) has glimpsed new details of how red giants—large, cool stars nearing death—spew dust into space. Astronomers observed three red giants named R Leonis, R Doradus (shown left), and W Hydrae. As the scientists report online today in Nature, each giant has a shell of dust located less than a single stellar diameter from the star's surface, where intense starlight pushes the dust into space via a wind that will strip the red giant's outer layers and turn it into a tiny white dwarf. The dust grains are about 6000 angstroms (600 nanometers) across—similar in size to the dust between stars—and likely consists of magnesium silicates such as forsterite and enstatite, or corundum, the tough mineral in rubies and sapphires, adding extra sparkle to a dying star's final days—as well as future gems for planets yet to be born.

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