Astronomers Discover Noble Gas Compound in Crab Nebula

It turns out that Earth isn't the only place where you can find a molecule containing a noble gas. Using an instrument aboard Europe's Herschel Space Observatory, researchers have discovered a noble gas, argon hydride, in the Crab Nebula.

The new discovery is the first of its kind. Before now, molecules of this sort have only been studied in laboratories on Earth. The noble gases, which include helium, argon, radon and krypton, usually do not react easily with other chemical elements and are often found on their own. In the right circumstances, though, they can form molecules with other elements. Yet scientists believed that these conditions simply do not occur in space.

"The Crab Nebula was only formed 1,000 years ago when a massive star exploded," said Haley Gomez, one of the researchers, in a news release. "Not only is it very young in astronomical terms, but also relatively close, at just 6,500 light years away, providing an excellent way to study what happens in these stellar explosions. Last year, we used the European Space Agency's Herschel Space Observatory to study the intricate network of gas filaments to show how exploding stars are creating huge amounts of space dust."

This discovery wasn't necessarily intentional, though. The scientists stumbled upon it almost by accident. They were concentrating on studying the dust in the filaments of the nebula when they spotted two bright emission lines exactly where they saw dust shining.

"At first, the discovery of argon seemed bizarre," said Mike Barlow, one of the researchers, in a news release. "With hot gas still expanding at high speeds after the explosion, a supernova remnant is a harsh, hot and hostile environment, and one of the places where we least expected to find a noble-gas based molecule."

The findings reveal that these molecules are indeed possible in the depths of space. The argon was produced in the initial stellar explosion, and then ionized with electrons stripped from the atoms in resulting intense radiation as shockwaves. These shockwaves led to the formation of the network of cool filaments containing cold molecular hydrogen, made of two hydrogen atoms. The ionized argon then mixed with the cool gas to create noble gas compounds.

The findings are published in the journal Science.