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The molecule that made the universe

Tuesday, 17 April 2012

Photo credit: NASA/JPL-Caltech

In a study that pushed quantum mechanical theory and research capabilities to the limit, UA researchers have found a way to see the molecule that likely made the universe - or at least the hot and fiery bits of it.

Lurking in the vast, chilly regions between stars, the unassuming molecule known as a triatomic hydrogen ion, or H3+, may hold secrets of the formation of the first stars after the Big Bang.

At the University of Arizona, then doctoral candidate Michele Pavanello spent months doing painstaking calculations to find a way to spot H3+ and unveil its pivotal role in astronomy and spectroscopy, supervised by Ludwik Adamowicz, a professor in the UA's department of chemistry and biochemistry.

The groundbreaking results have been published in a recent edition of Physical Review Letters.

"Most of the universe consists of hydrogen in various forms," said Adamowicz, "but the H3+ ion is the most prevalent molecular ion in interstellar space. It's also one of the most important molecules in existence."

Believed to be critical to the formation of stars in the early days of the universe, H3+ also is the precursor to many types of chemical reactions, said Adamowicz, including those leading to compounds such as water or carbon, which are essential for life.

Early stars would have become hotter and hotter until they exploded before they ever formed, according to Pavanello, unless there was a way to release some of that pent-up energy.

"There wouldn't be any star formation if there weren't molecules that slowly cool down the forming star by emitting light," said Pavanello. Not many molecules can do that, he added, partly because very few molecules existed in the early days of the universe.

"Astronomers think that the only molecule that could cool down a forming star in that particular time is H3+."

A perfect asymmetry

Another molecule, molecular hydrogen, would have been present, but it would have had a much harder time cooling a forming star than H3+. "Hydrogen does not like to emit light, while H3+ can bend and vibrate, and in doing so it is able to emit light." said Pavanello.