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Astronomers Have Spotted the Universe's First Molecule (sciencemag.org)
Astronomers have detected the universe's first molecule. "Helium hydride (HeH), a combination of helium and hydrogen, was spotted some 3000 light-years from Earth by an instrument aboard the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA), a telescope built into a converted 747 jet that flies above the opaque parts of Earth's atmosphere," reports Science Magazine. The findings have been reported in the journal Nature. From the report: HeH has long been thought to mark the "dawn of chemistry," as the remnants of the big bang cooled to about 4000 K and ions began to team up with electrons to form neutral atoms. Researchers believe that in that primordial gas, neutral helium reacted with hydrogen ions to form the first chemical bond joining the very first molecule. In 1925, chemists synthesized HeH in the lab. In the 1970s, theorists predicted that the molecule may exist today, most likely formed anew in planetary nebulae, clouds of gas ejected by dying sunlike stars. But decades of observations failed to find any, casting doubts on the theory.
To find the elusive molecule, astrochemists search for characteristic frequencies of light it emits, particularly a spectral line in the far infrared typically blocked by Earth's atmosphere. But a far-infrared spectrometer aboard SOFIA allowed them to find that signature for the first time, in a planetary nebula called NGC 7027, the researchers report today in Nature. The result shows this unlikely molecule -- involving typically unreactive helium -- can be created in space. With this cornerstone confirmed, it appears that the evolution of the following 13 billion years of chemistry stands on firmer ground.
To find the elusive molecule, astrochemists search for characteristic frequencies of light it emits, particularly a spectral line in the far infrared typically blocked by Earth's atmosphere. But a far-infrared spectrometer aboard SOFIA allowed them to find that signature for the first time, in a planetary nebula called NGC 7027, the researchers report today in Nature. The result shows this unlikely molecule -- involving typically unreactive helium -- can be created in space. With this cornerstone confirmed, it appears that the evolution of the following 13 billion years of chemistry stands on firmer ground.
You should try to read the text again, where it says in the last paragraph that they look for the spectral lines that shows what molecules are present.
It isn't the actual first HeH molecule, because that would be impossible to determine, so read it as the 'first type of molecule', ie. a combination of different types of atoms, where H and He were the first.
Hmm, that's not the definition of molecule *I* was taught in school.
And oddly enough, that's not the definition of molecule I find in dictionaries, online or offline....
"I do not agree with what you say, but I will defend to the death your right to say it"
RTFA: With their higher ionization potentials, the helium ions He2+ and He+ were the first to combine with free electrons, forming the first neutral atoms; the recombination of hydrogen followed. In this metal-free and low-density environment, neutral helium atoms formed the Universe’s first molecular bond in the helium hydride ion HeH+ through radiative association with protons. As recombination progressed, the destruction of HeH+ created a path to the formation of molecular hydrogen.