As the most abundant element around and the basis for a full three-quarters the mass of the universe, you'd think scientists would have uncovered all there is to know about hydrogen. Apparently, they haven't, as researchers at the Carnegie Institution for Science have just produced a third version of the element in a lab, that they believe is found on gas giant planets like Jupiter and Saturn. They're calling it dark hydrogen.
To arrive at their conclusion, Carnegie's Alexander Goncharov and the University of Edinburgh's Stewart McWilliams simulated the pressure that would be found on gas planets between their surfaces – where hydrogen is a gas (called molecular hydrogen) – and their cores, where it's a liquid metal (called metallic hydrogen). To do this, they employed a laser-heated diamond anvil cell. Used frequently in science to create extreme pressure, this piece of equipment consists of two diamonds whose tips can compress a material to extreme degrees.
In this instance, the team compressed hydrogen under pressures ranging from 10,000 to 1.5 million times normal atmospheric pressure.
During the compression, a version of hydrogen formed that didn't reflect or transmit light, thus its "dark" monicker. This dark hydrogen was somewhere between a gas and a metal, and was able to transmit electricity, but only weakly.
The discovery has two implications for planetary studies. One is that the element's heat transmission properties could help explain how heat easily leaves gas giant planets. The other is that thanks to its conductivity, it could be involved in producing gas giants' magnetic fields.
Previously, researchers at the University of Edinburgh had produced metallic hydrogen in the lab, at pressures equal to 3.25 million times that of Earth's atmosphere.
The new discovery was published Wednesday in the journal Physical Review Letters.
Source: Carnegie Institution for Science
