All that Glitters

When you look at the night sky, of course you see stars glittering up there. And, planets.  And, if you  have a telescope, you can make out the blurry wisps of nebulae and galaxies.  Nebulae are clouds of gas and dust that float in space. They can be starbirth regions, the outpouring of a star (or stars) dying, and a mixture of both.

As it turns out, when you look at the clouds of gas and dust (called circumstellar disks) surrounding some special types of stars, you are looking at something else that glitters: diamonds.  In these regions, there are countless numbers of these tiny sparklers (and I do mean tiny — most are not even the width of a human hair) swarming around in those disks. Yet around some stars, there are enough diamond specks that if you packed them all together, they’d have enough mass to make a tiny moonlet.

How can diamonds form in space? It’s a detective story, really, and a group of scientists from Japan, Germany, and Denmark used Subaru telescope on Mauna Kea in Hawai’i, to study ayoung star called Elias 1 to solve the central riddle of that story: how can diamonds form in space?

When scientists look for diamonds in space, they are like detectives using fingerprints to trace a missing person or find the perpetrator of a crime. The fingerprints of diamond crystals take the form of  lines in the infrared wavelength of light, outside the range of visible light. The first such signature was discovered in 1983 in the circumstellar disk of Elias 1, a young star located in the direction of Taurus. It is is one of many Herbig Ae/Be (HAEBE) stars?young, very bright stars that are about 1.5-10 times as massive as our Sun.

The research team began with clues from previous laboratory research into how diamonds are formed (carbon materials are subjected to  great temperatures and pressures).  They coupled this with observations of stars that are surrounded by dust, and have partner stars that emit tremendous bursts of hard x-ray emissions.   X-rays are emitted under extremely energetic and hot conditions, so that supplies the necessary energy and pressure for a natural diamond factory in space.

The scientists knew from their research that diamonds are formed close to the stars where they exist. They aren’t floating in from random points in space.  Also, diamond stars must have special ingredients: that disk full of carbon material, a hot central star and a companion emitting hard x-rays. The star must be of intermediate mass that can warm up the disk to a medium temperature. Then, carbon onions can form, providing the cradle for diamond creation. The need for such special conditions would explain why we see so few stars with diamond signatures in their disks.

The findings of this research (more details here) will raise even more questions and speculation about the formation of these fascinating crystals. It’s possible that there are tons of diamonds that astronomers cannot yet see because their emissions are hidden from view by shells of material surrounding the stars where they exist.