The discovery of silicate crystals around stars by Europe’s Infrared Space Observatory (ISO) promises to open a new field of astronomy dubbed "astromineralogy," astronomers said last week. While astronomers had known that silicates existed in dust clouds, they had assumed it was only in an amorphous form, and not in crystals as found in minerals, according to Dutch astronomer Rens Waters.
The crystals, found in dust disks around old stars as well as new protoplanetary disks, are formed when materials are heated to temperatures above 1,300 degrees Celsius (2,372 degrees Fahrenheit) and then allowed to cool slowly, thus providing clues to their formation. One mystery, though, is that ISO failed to detect silicate crystals in the interstellar medium.
"Crystalline silicates are synthesized around the stars; then that dust goes into the interstellar space, and enriches the raw material out of which more stars and planets will form," said Waters. "So you would expect crystals also to be in the interstellar medium!"