The molecule known as H3+ is believed to have had a vital role in cooling down the first stars of the universe, and may still play an important part in the formation of current 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. In the presence of the radiation that pervades interstellar space, H3+ can gain energy that causes it to vibrate and lose its symmetry. Here, the electrons are shared among only two of the hydrogen atoms. Asymmetries such as these allow the molecule to emit light and cool down forming stars.
"Most of the universe consists of hydrogen in various forms," said Ludwik Adamowicz, a professor in the University of Arizona''s department of chemistry and biochemistry, 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 Michele Pavanello, who led the groundbreaking research, 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+."