Noble Gas That Shouldn't be Able to Form in Space Discovered in Crab Nebula by Accident
Researchers found a molecule containing a noble gas where they weren't expecting it.
The molecule, called argon hydride, was found in a crab nebula; before this groundbreaking discovery this type of particle had only ever been analyzed in a laboratory, a Cardiff University news release reported.
Noble gases (helium, argon, radon and krypton) do not easily react with other elements and are usually loners. In some rare circumstances they can create molecules with other elements, but scientists had previously believed this could never happen in outer space.
"The Crab Nebula was only formed 1000 years ago when a massive star exploded", said Dr Haley Gomez of Cardiff University's School of Physics and Astronomy. "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."
Measurements of the Crab Nebula were made using Herschel's SPIRE instrument. Alien spinning molecules give off specific wavelengths (colors) of light referred to as "emission lines." Researchers are able to determine the "chemistry" of outer space by looking at these lines.
The team basically made the discovery by accident.
"We were really concentrating on studying the dust in the filaments with SPIRE, and out pops these two bright emission lines exactly where we see the dust shining", Doctor Haley Gomez of Cardiff University's School of Physics and Astronomy said. "The team had a hard time figuring out what these lines were from, as no-one had seen them before."
"At first, the discovery of argon seemed bizarre. 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," study leader Professor Mike Barlow from University College London, said.
The team believes they have pinpointed a Crab Nebula as one of the few regions of space that provides the right conditions for these molecules to form.
The argon is believed to have been produced when the star exploded and energized. This caused "cool filaments" containing cold molecular hydrogen to form. The ionized argon may have paired up with the gas, providing conditions friendly to noble gas formation.
"Finding this kind of molecule allowed us to evaluate the type (or isotope) of argon we discovered in the Crab Nebula," Gomez said. "We now know that it is different from argon we see in rocks on the Earth. Future measurements will allow us to probe what exactly took place in the explosion 1000 years ago."
"What a great detective story," Professor Matt Griffin, from Cardiff University, and lead scientist of the team behind the SPIRE instrument, said. "Here we see the excellent performance of the Herschel-SPIRE spectrometer, the expertise of the instrument team in producing the highest quality data, and the tenacity and vision of the scientists [analyzing] it, all coming together to make an intriguing new discovery."