Detection of Diamond Dust Around Distant Stars Solves Decades-Long Mystery

[Judi Lynn]

George Dvorsky
Today 6:00 pm

For years, astronomers have struggled to understand the source of anomalous microwave emissions coming from various locations across the Milky Way galaxy. A recently concluded survey of the planet-forming disks around young stars suggests these strange transmissions are being produced by something rather extraordinary: dense clouds of microscopic diamonds.

The appropriately named “anomalous microwave emissions” (AMEs) were first detected two decades ago. The faint microwave light originated from a number of regions across the Milky Way, and while scientists didn’t have an explanation for the observation, it was proposed that some type of particle was responsible. A popular theory was that AMEs were being produced by an organic molecule known as polycyclic aromatic hydrocarbons (PAHs). These carbon-based molecules are scattered throughout space, and they feature a distinct, yet faint, infrared signature.

New research published today in Nature Astronomy suggests this interpretation was wrong, and that clouds of nanodiamonds located within embryonic star systems are the true source of AMEs. Nanodiamonds are naturally forming bits of crystalline carbon, and with radii between 0.75 to 1.1  nanometers, they’re hundreds of thousands of times smaller than a grain of sand. These extremely tiny bits of gemstones arise within protoplanetary disks, and they’re often found inside meteorites that have fallen to Earth.

For the study, an international team of astronomers analyzed the protoplanetary disk of 14 infant stars using the Green Bank Telescope (GBT) in United States and the Telescope Compact Array (ATCA) in Australia. The AME signal was detected in three of these stars, V892 Tau, HD 97048, and MWC 297. These three star systems produced the characteristic infrared signal associated with hydrogenated nanodiamonds, that is, nanodiamonds with hydrogen-bearing molecules on the surface. Hydrogenated nanodiamonds emerge from the superheated vapor of carbon atoms in high-energy, star-forming regions of space. Like PAHs, nanodiamonds also glow in the infrared portion of the light spectrum, but at a different wavelength.

More:
https://gizmodo.com/detection-of-diamond-dust-around-distant-stars-solves-d-1826734789