The helium hydride ion (HeH+), possibly the first molecule in existence, has been discovered in space, according to an article by CNN. Believed to be formed by the first chemical reaction of the big bang, helium hydride has long been hypothesized but only recently located in outer space. How are molecules made?
The CNN article said that scientists flew a modified Boeing 747SP jet called SOFIA—the Stratospheric Observatory for Infrared Astronomy—above Earth’s lower atmosphere and detected Helium Hydride with a high-resolution spectrometer. The discovery raises questions about how molecules are formed and why scientists must find them and prove they exist.
Making a Nucleus from the Big Bang
Where did all of the different elements of the periodic table of elements start out? What brought them into existence? Every atom has a nucleus, and all the nuclei are formed in a process called nucelosynthesis. “There are four main processes,” Dr. Lawrence Weinstein, Professor of Physics at Old Dominion University, said. “There’s big bang nucleosynthesis, which made the hydrogen and helium; there’s fusion in ordinary stars, which made helium, carbon, and oxygen; there’s cosmic-ray fission, where fast protons collide with carbon to make nuclei skipped over in stars; and there are explosive processes with supernova or colliding neutron stars.”
Immediately after the big bang—approximately one microsecond—the temperature of the universe cooled to about 100 million electron volts, or 10 billion kelvins. This process allowed subatomic particles called quarks to begin colliding and sticking together to form protons and neutrons. Three minutes later, the temperature plummeted to 100,000 electron volts, which is a perfect temperature for nucleosynthesis.
“To make nuclei from neutrons and protons, the neutron has to hit a proton and form a deuterium nucleus—that’s heavy hydrogen—and give off a gamma ray,” Dr. Weinstein said. He explained that if the temperature were too high, the deuterium would fall apart and get destroyed. If the temperature were too low, the deuterium, protons, and neutrons would “freeze out,” or become too stable to bond and to synthesize a nucleus.
The Big Bang, Black Holes, Neutron Stars, and Heavy Metal
“When a star exhausts its hydrogen, then it gravitationally shrinks because it’s lost its power source,” Dr. Weinstein said. “As it gravitationally shrinks, it actually gets hotter, and it gets hotter and hotter until it finds a new power source.” Eventually it fuses helium-4 and causes a chemical reaction that burns off the helium and leads to the creation of both carbon and oxygen, two heavier elements than helium.
“If the star is big enough, which means more than eight times the mass of the Sun, then carbon begins burning in the core,” Dr. Weinstein said. This process can begin a chain reaction of burning off and producing heavier elements all the way up to iron, where it hits a proverbial ceiling. Finally, this mass of iron has a gravitational spike at its core that increases the temperature further, causing the iron to become an incredibly dense and ever-collapsing core. Depending on its core mass, this object will either become a neutron star and go supernova or it will become a black hole, sucking in matter so strongly that not even light can escape.
The creation of the various elements is a complex process involving chemistry, alchemy, astrophysics, and nuclear physics. With the confirmation of helium hydride in space, an important piece of the puzzle falls into place surrounding the big bang and the creation of the universe.
Dr. Lawrence Weinstein contributed to this article. Dr. Weinstein is a Professor of Physics at Old Dominion University and a researcher at the Thomas Jefferson National Accelerator Facility. He received his undergraduate degree from Yale University and his doctorate in Physics from the Massachusetts Institute of Technology.