Public Release: 

Discovery in the sky with nanodiamonds

Tiny particles of diamond responsible for mysterious source of microwaves across the Milky Way

Cardiff University

A faint and mysterious stream of microwaves emanating from star systems far out in the Milky Way could be caused by tiny diamonds, new research has suggested.

For decades scientists have been able to measure this 'glow' of microwave light, dubbed the anomalous microwave emission (AME), coming from a number of regions in the night sky, but have yet to identify its exact source.

In a new study led by researchers at Cardiff University and published today in the journal Nature Astronomy, an international team has shown that it is likely the microwaves are coming from tiny crystals of carbon, otherwise known as nanodiamonds, inside of dust and gas that surrounds newly formed stars.

This collection of dust and gas, known as a protoplanetary disk, is where planets begin to form and contains a whole host of organic molecules. The extremely hot and energized conditions within these disks are ideal for nanodiamonds to form.

Indeed, the nanodiamonds within protoplanetary disks, which are hundreds of thousands of times smaller than a grain of sand, are often found in meteorites on Earth.

"We knew that some type of particle was responsible for the microwave light, but its precise source has been a puzzle since it was first detected nearly 20 years ago," said lead author of the study Dr Jane Greaves from Cardiff University's School of Physics and Astronomy.

"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."

To arrive at their results the team honed in on three young stars that were emitting AME light using the Robert C. Byrd Green Bank Telescopes in West Virginia and the Australia Telescope Compact Array.

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

The team noted that the unique signal came from hydrogenated nanodiamonds, in which the crystalline carbon structure is surrounded by hydrogen-bearing molecules on its surface.

"This is a cool and unexpected resolution of the puzzle of anomalous microwaves radiation," Dr 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."

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Notes to editors

1. For further information contact:
Michael Bishop
Communications & Marketing
Cardiff University
Tel: 02920 874499 / 07713 325300
Email: BishopM1@cardiff.ac.uk

2. Cardiff University is recognised in independent government assessments as one of Britain's leading teaching and research universities and is a member of the Russell Group of the UK's most research intensive universities. The 2014 Research Excellence Framework ranked the University 5th in the UK for research excellence. Among its academic staff are two Nobel Laureates, including the winner of the 2007 Nobel Prize for Medicine, Professor Sir Martin Evans. Founded by Royal Charter in 1883, today the University combines impressive modern facilities and a dynamic approach to teaching and research. The University's breadth of expertise encompasses: the College of Arts, Humanities and Social Sciences; the College of Biomedical and Life Sciences; and the College of Physical Sciences and Engineering, along with a longstanding commitment to lifelong learning. Cardiff's flagship Research Institutes are offering radical new approaches to pressing global problems. http://www.cardiff.ac.uk

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