How dying stars spew out the material of future planets

While stars like our Sun are known to eject much of their mass in their final years, it has remained unclear just how the dust is blown away.

Scientists reporting in Nature describe an astronomical study of extraordinary resolution to tackle the mystery.

They found dust grains of nearly a millionth of a metre across, big enough to be pushed out by dying stars' light.

What has confused astronomers until now is just how that material is expelled; computer models of the process suggest that particles coming from the stars should be so small that they would simply absorb the light around them and undergo significant heating.