The more we try to answer questions about the so-called “Big Bang,” which scientists believe occurred 13.8 billion years ago, and the evolution of the universe, the more challenging it gets to do so. However, scientists believe they have detected the universe’s first molecule. They believe these early molecules were essential in the evolution of the world as we know it today, although those molecules are absent now.
Researchers have long believed the helium hydride ion HeH+ was the universe’s first molecule. However, until now, researchers couldn’t find any evidence of its existence. They reported their discovery in a paper published in the journal Nature.
Scientists say that after the Big Bang took place, HeH+ formed a molecular bond when helium atoms and protons combined. However, the bonds were later broken apart into hydrogen molecules and helium atoms. Researchers believe both of those elements to be the most dominant in the universe, with hydrogen being the most abundant and helium following right behind.
Researchers first demonstrated the molecular ion in a lab in 1925 and studied it, which is why researchers have been searching for HeH+ in space for decades.
“The chemistry of the universe began with HeH+. The lack of definitive evidence of its very existence in interstellar space has been a dilemma for astronomy for a long time,” study author and astronomer Rolf Güsten of the Max Planck Institute for Radioastronomy said in a statement.
Scientists used different astrochemical models in the late 1970s and found a “detectable possibility” of HeH+ being the universe’s first molecule. Then they believed HeH+ might still exist in a planetary nebula ejected by stars like the sun in the life stage before their supernova explosion.
Researchers say they found it difficult to detect the signal of the universe’s first molecule at its strongest wavelength. Due to Earth’s opaque atmosphere, researchers couldn’t use ground-based telescopes. Thus, they had to use the Stratospheric Observatory for Infrared Astronomy, also known as SOFIA, which is a Boeing jet modified to carry a telescope which can fly above Earth’s lower atmosphere. SOFIA was also equipped with high-resolution spectrometer called GREAT, which detected the molecule in the planetary nebula NGC 7027.
“The discovery of HeH+ is a dramatic and beautiful demonstration of nature’s tendency to form molecules,” study co-author and Johns Hopkins professor David Neufeld said in a statement. “Despite the unpromising ingredients that are available, a mixture of hydrogen with the unreactive noble gas helium, and a harsh environment at thousands of degrees Celsius, a fragile molecule forms. Remarkably, this phenomenon can not only be observed by astronomers but also understood using theoretical models that we have developed.”
The researchers said in their study that this offers the first “definitive evidence” of its existence in the universe. They believe their study also confirms previous theories about the universe’s first molecule.