Clodius and Co. Blog
June 14th, 2018
After more than 20 years of Sherlock Holmes-like sleuthing, scientists are crediting teeny, rapidly spinning diamonds for generating the curious microwave "glow" coming from a number of regions in the night sky.

In a new study led by researchers at Great Britain's Cardiff University and published earlier this week in the journal Nature Astronomy, an international team has shown that it is likely the microwaves emanating from star systems far out in the Milky Way are coming from tiny crystals of carbon, otherwise known as nanodiamonds, inside of dust and gas that surrounds newly formed stars.

For decades scientists have been able to measure a faint and mysterious stream of microwaves, dubbed the anomalous microwave emission (AME), but could never pinpoint the exact source. The microwaves seemed to be emanating from clouds of "spinning dust."

"In a Sherlock Holmes-like method of eliminating all other causes, we can confidently say the best and likely only candidate capable of producing this microwaves glow is the presences of nanodiamonds around these newly formed stars," said lead author of the study Dr. Jane Greaves from Cardiff University's School of Physics and Astronomy.

Scientists used high-powered telescopes in West Virginia and Australia to monitor three young stars that were known to emit AME light.

By studying the infrared light that was coming from the protoplanetary disks surrounding the stars, the team was able to match the infrared light with the unique signature that is naturally given off by nanodiamonds.

The team noted that the unique signal came from rapidly spinning, hydrogenated nanodiamonds. These minuscule particles — hundreds of thousands of times smaller than a grain of sand — have a crystalline carbon structure surrounded by hydrogen-bearing molecules on its surface. The nanodiamonds can occur, say the scientists, when carbon atoms become superheated in the highly energized star-forming regions of space.

"This is a cool and unexpected resolution of the puzzle of anomalous microwaves radiation," Greaves continued. "It's even more interesting that it was obtained by looking at protoplanetary disks, shedding light on the chemical features of early solar systems, including our own."

Credit: Image by S. Dagnello, NRAO/AUI/NSF.