The first type of molecule to ever form in the universe has been observed in space for the first time. The observation of the molecule, known as helium hydride, was possible thanks to NASA’s airborne telescope the Stratospheric Observatory for Infrared Astronomy, or SOFIA.
Only hydrogen, helium, and lithium formed during the Big Bang, and hydrogen and helium made up most of the elemental matter. Therefore, it is not surprising that about 100,000 years after the Big Bang, the first molecule to form was a curious interaction between a helium atom and a positive hydrogen ion.
While the universe has changed over the last 13.7 billion years, researchers believed that the molecule could still be found in space. As reported in the journal Nature, the molecule was discovered by SOFIA in a planetary nebula within our own galaxy. The Nebula NGC 7027 is located 3,000 light-years from Earth and has the right conditions for the molecule to form.
“The lack of evidence of the very existence of helium hydride in interstellar space was a dilemma for astronomy for decades,” lead author Rolf Guesten, of the Max Planck Institute for Radio Astronomy in Bonn, Germany, said in a statement. He was aboard the aircraft that carries SOFIA when the observation was made.
“It was so exciting to be there, seeing helium hydride for the first time in the data. This brings a long search to a happy ending and eliminates doubts about our understanding of the underlying chemistry of the early universe,” he added.
Planetary nebulae are formed by a red giant during the later stages of its life. These types of stars are extremely puffy and their outer layers are pushed outwards by an extremely hot stellar core. This particular environment is ideal for the formation of helium hydride. The molecule does not form easily; being a noble gas, helium has no reason to form molecules.
Since 1925, scientists have found ways to make the fussy atom share an electron with a hydrogen nucleus, and similar conditions can be found in the hot and ultraviolet-dominated environment of a planetary nebula.
The discovery of this compound in space confirms ideas about the chemistry of the very early universe. The presence or absence of certain molecules plays a role in the formation of stars, and knowing what was present back then is crucial to understanding the still unobserved first stars of the cosmos.