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Astronomers Have Spotted the Universe's First Molecule (sciencemag.org) 71

Posted by BeauHD from the dawn-of-chemistry dept.
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.
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Astronomers Have Spotted the Universe's First Molecule More

Astronomers Have Spotted the Universe's First Molecule

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  • Meanwhile (Score:1)

    by Anonymous Coward

    Astronomers find a molecule 3000 light years away, meanwhile I can't find the remote control which is somewhere on the same sofa I'm sat on

  • I don't believe it (Score:2, Interesting)

    by Joce640k ( 829181 )

    It's a big universe and there's a lot of HeH molecules out there. How do they know this is the first one?

    (...and how do they even see a molecule from 3000 light years away? This "discovery" is very implausible to me)

    • Re:I don't believe it (Score:4, Informative)

      by lalleglad ( 39849 ) on Thursday April 18, 2019 @05:41AM (#58453270)

      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.

      • Re:I don't believe it (Score:4, Insightful)

        by RobinH ( 124750 ) on Thursday April 18, 2019 @06:00AM (#58453334) Homepage
        Yeah, I would have though H2 would be the first molecule.

        • Re: (Score:1)

          by Anonymous Coward

          Compound rather than molecule

        • Re: (Score:1)

          by Anonymous Coward

          Yeah, I would have though H2 would be the first molecule.

          The thinking is that by this time when such atoms could form, the universe was still in a state where molecules were hindered from forming as they do naturally today.

          A search term for you is recombination era [wikipedia.org]

          I'm not going to pretend I understand the goings on, but a quick summary says the universe expanding caused a very low density of those atoms, and there was a lack of solid catalyzers to help form molecules.
          Apparently the radiation came into play to conspire against molecules forming too.

          So in that part

        • Re: (Score:3, Informative)

          by Anonymous Coward

          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.

        • It may have been initially too hot for H2 to form. The underlying report indicates that HeH+ was the first molecule and that molecular hydrogen (H2) followed.

          • Yeah, I thought that at first. But the temperature range typically given for the condensation of hydrogen nuclii and electrons into monatomic hydrogen (the formation of what is now the cosmic microwave background, after around 40x stretching of space) is at several thousands of K, which would be in the orange- to green- hot temperature range. To allow something to form with an absorption band in the "far IR", you'd need to drop the temperature to somewhere below a thousand K.
        • IIRC, it would have been too early for first generation stellar nucleosynthesis to generate oxygen.
        • Your reasoning (and mine) is probably that hydrogen is the simplest atom, and you need hydrogen to fuse inside stars to form helium. Ergo there should have been lots of hydrogen around to form H2 before helium showed up.

          But double-checking the cosmology, apparently there was enough energy in the big bang to form substantial amounts of helium along with the hydrogen. So the two atoms existed together before stars began forming. And the bonding energies mean HeH was easier to form in that environment tha

      • Re:I don't believe it (Score:4, Informative)

        by CrimsonAvenger ( 580665 ) on Thursday April 18, 2019 @06:09AM (#58453356)

        so read it as the 'first type of molecule', ie. a combination of different types of atoms,

        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....

      • 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.

        I have to read the headline in a special way that changes its meaning? How do I know to do that?

        We can detect single photons and every photon comes from inside a single atom. In theory you can detect single molecules by their emissions at any distance. This just leaves the question of how they know this molecule is "the one".

        • I have to read the headline in a special way that changes its meaning? How do I know to do that?

          Where things don't quite seem to add up, and you have reason to suspect the involvement of journalists who are journalists, not scientists. Then you have to read much more carefully. Sad, but true.

          Reading press releases or commentary instead of the actual paper is normally a waste of time and electrons if you actually want to understand the science.

          The paper in question is here [nature.com], but you'll need either access to

          • Where things don't quite seem to add up, and you have reason to suspect the involvement of journalists who are journalists, not scientists. Then you have to read much more carefully. Sad, but true.

            How do you know the correct interpretation. That sounds like religion - everybody "interpreting" instead of just looking at the words written on the page.

            • In the case of uncertainty, go to the original paper. That is why they are published, reviewed before publication, consulted between authors and colleagues (often also competitors in the field with the original authors). All things that don't happen in the journalism industry.

              I mean, if you think it sounds like religion, then I'd say "If I wanted to know what a Roman-era Jew said, I'd look for documents written in the Roman era by people with at least some possibility of actually having been within a few g

      • Comment removed based on user account deletion
        • To quote the abstract, not the press release, "During the dawn of chemistry, when the temperature of the young Universe had fallen below some 4,000 kelvin, the ions of the light elements produced in Big Bang nucleosynthesis recombined in reverse order of their ionization potential. 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 envi
          • Comment removed based on user account deletion
            • It's one of the aspects of the oft-complained about "lack of critical thinking". Which goes with "journalists" being ... well, as my now-deceased friend and a part-time lecturer in Journalism after running news rooms for 30-plus years would say, "staff writers". Journalists do take the time to check the sources, read the surrounding documents, and think carefully about their articles. Someone who has to turn out something to garner 3000-ad clicks or there is no food on the table tonight ... a writer yes, bu

    • Re: (Score:3, Funny)

      by The Grim Reefer ( 1162755 )

      It's a big universe and there's a lot of HeH molecules out there. How do they know this is the first one?

      (...and how do they even see a molecule from 3000 light years away? This "discovery" is very implausible to me)

      Well considering the universe is 6000 years old and the earth is at the center of creation I would think it's obvious. Plus God gave me a certificate of authenticity. She's nice like that.

  • Helium and Hydrogen? (Score:3, Funny)

    by Anonymous Coward on Thursday April 18, 2019 @06:11AM (#58453362)

    I'd say it wasn't particularly noble of Helium to hook-up with lowly Hydrogen. Not by a long shot.

  • ... i.e. a He+ ion plus neutral H forming a positive HeH+ ion. That's quite different from neutral HeH.

    Also while they found HeH+ in that nebula that's not some remnant from the big bang (as far as i understand), but it's interesting to look at the HeH+ in NGC7027 to compare our modeling of reactions involving HeH+ to the astronomical observations.

  • Where did the components of these molecules come from? How did they get there?

    • Big bang nucleosynthesis

    • Hydrogen (H+) is just a proton. Helium (He+) is two protons. (if you want to get into isotopes we can involve neutrons but I digress). In short these are about as simple as you can get while being more than elementary particles.

      • Re: (Score:2)

        by cfa22 ( 1594513 )
        He+ also has a single electron.
      • He-3 (proton+proton+neutron) is the lowest stable nucleus of Helium. I don't have a figure off-hand for the half-life of the di-proton (proton+proton) with respect to decaying to a deuteron (proton+neutron) plus electron plus neutrino, but it's probably not as long as the half life of the hydrogen atom compared to the hydrogen ion, in the plasma conditions we're talking about. Probably not by many orders of magnitude - weak force interactions tend to be a lot quicker than electromagnetic ones.
  • So that's where I left it!
  • The furthest known star is 13.26 billion light-years from earth. I would bet that there are more than a few HeH+ molecules there, seeing that stars are made up of Hydrogen and Helium. Why only 3000 light years?
    • Yeah I had the same reaction, until I figured out what they meant. They are not saying those particular molecules are the oldest, but molecules of this type had to be the first created in the universe. Assuming H atoms formed first, then those formed He atoms, and then those combined into HeH, since that was all that existed.

  • Ahhh, baby universe molecules, they're so cuuute! bi bi bi gootchi gootchi goo...

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