This artist's concept illustrates how silicate crystals like those found in comets can be created by an outburst from a growing star. The image shows a young sun-like star encircled by its planet-forming disk of gas and dust. The silicate that makes up most of the dust would have begun as non-crystallized, amorphous particles.

As streams of material spiral from the disk onto the star, its mass increases and it brightens and heats up dramatically. The resulting outburst causes temperatures to rise in the star's surrounding disk.

When the disk warms from the star's outburst, the amorphous particles of silicate melt. As they cool off, they transform into forsterite (see inset), a type of silicate crystal often found in comets in our solar system.

In April 2008, NASA's Spitzer Space Telescope detected evidence of this process taking place on the disk of a young sun-like star called EX Lupi.