‘Sweet Spots’ for Formation of Complex Organic Molecules Discovered in Our Galaxy

Article Updated: 26 Apr , 2016
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Astrobiologists have discovered regions in our galaxy which might have the greatest potential for producing very complex organic molecules, the starting point for the development of life. We’ve heard before about “follow the water” in the search for life; in this case it may be “follow the methanol”…

The scientists involved, from Rensselaer Polytechnic Institute in Troy, New York, began a search for methanol, a key ingredient in the synthesis of organic molecules. According to Douglas Whittet, lead researcher of the study, “Methanol formation is the major chemical pathway to complex organic molecules in interstellar space.” The idea is to look for areas where there is rich methanol production occurring. In the large clouds of dust and gas that give birth to new stars, there are simpler organic molecules like carbon monoxide. Under the right conditions, carbon monoxide on the surfaces of dust grains can interact with hydrogen, also found in the clouds, to create methanol. Methanol can then become a steppingstone to create the more complex organic molecules, the types needed for life itself. But how much methanol is out there, and where?

It appears to be most abundant around a small number of newly-formed stars, where it makes up to 30 percent of the material around those stars. In other areas though, it is in much smaller amounts, or none at all. In the cold dust and gas clouds that will eventually produce new stars, it was found to exist in the 1 to 2 percent range. Hence, there appear to be “sweet spots” where conditions are suitable for the chain reactions to occur, depending on how fast the needed molecules can reach the dust grains. It can mean the difference between a “dead end” for additional development or an “organic bloom.” As described by Whittet: “If the carbon monoxide molecules build up too quickly on the surfaces of the dust grains, they don’t get the opportunity to react and form more complex molecules. Instead, the molecules get buried in the ices and add up to a lot of dead weight. If the buildup is too slow, the opportunities for reaction are also much lower.”

So some places may be much more likely to have the conditions necessary for the development of life than others. What about our own solar system? How does it compare? By studying the methanol amounts in comets, relics from the beginning of the solar system, the scientists have concluded that the methanol abundance back then was about average. Not a dearth of the stuff, but not a “sweet spot” really, either. Yet here we are… or, as Whittet put it, “This means that our solar system wasn’t particularly lucky and didn’t have the large amounts of methanol that we see around some other stars in the galaxy. But, it was obviously enough for us to be here.”

The paper, titled “Observational constraints on methanol production in interstellar and preplanetary ices,” will be published in the Nov. 20 edition of The Astrophysical Journal and is a collaboration between Rensselaer, NASA Ames Research Center, the SETI Institute and Ohio State University.

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5 Responses

  1. Anonymous says:

    Could life exist in a stellar disk?

    I don’t think this happened in our solar system, and I am not a fan of panspermia. However, it occurred to me that life on planets is pretty much confined to the skinny near-surface region of earth-sized planets, where the whole volume of an accretion disk has access to organic materials and the star as an energy source.

    Life like us requires liquid water. Life in vacuum and near weightlessness might work differently. It would have to be a lot colder so as not to boil away, but it might use light to achieve reactions that would not occur naturally at the ambient temperatures. I could imagine some very open, dendritic structure that might trap suitable molecules and use them to grow.

    • Anonymous says:

      This data indicates that organic molecules can form under a range of conditions, including those in space. I think that organic molecules were likely formed on the early Earth as much as they can chemically form in space. The occurrence of organic molecules in space, as seen in nebula and the interstellar environment, tells us more about the wide range of conditions under which such chemicals can form,

      What we call biology requires water and carbon based organic molecules with oxygen, nitrogen and so forth. There may be other very complex systems in the universe that operate on different principles. These might have properties in common with biology, but in other ways may be very different. The surface of a neutron star could be a region with very complex structures, and I think planetary rings could turn out to have extremely complex systems. We might hesitate calling these structures life, for life as I see it involves organic molecules in water solution and a nucleotide sequence which is the information template for biological structures.

      LC

    • Torbjörn Larsson says:

      Good question.

      The large volume is the transpermia argument for why comets would have life. A few weeks back a paper showed that the liquid water zone for an aggregating body would move too fast for making abiogenesis likely unless the body is really large. So in reality a few bodies would be candidates, not all of the asteroids or comets.

      Something similar happens in these disks, I think. During planetary disk formation towards planets, a lot of fast chemical processing is happening in the disk as dust is transported to and from the vicinity of the fledgling star. So in reality these sweet spots would be temporary hot spots for chemical evolution, again making difficulties for such ideas.

      You would have to model it, but I believe in the cold regions radiation would break down structures faster than they could utilize the energy for some form of constructive metabolism. For example, DNA degrades fast in space even when frozen.

      I will have to differ with lcrowell on the biology here though. I would define biology as the evolutionary process among biochemical structures*, and life as the populations that partake in this process**. I don’t think we need to have other names for similar systems, with a loose definition of “similar”.

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      * Just to make biologists happy that they don’t need to study soft- and hardware in addition to all the wetware!

      ** Populations rather than individuals. The NASA definition of life (evolution and metabolism) is great for detecting specimen quickly, not so great to identify such habitats you describe. Evolution happens for a population, not individuals as such, and sometimes you have to embrace that.

      • Anonymous says:

        Our first ‘life-like’ contact may be disappointing. There may be something that grows slowly, and bits bud or drop off, and a few of these manage to grow in a similar way. Some people will argue it is life, and others will argue it is just crystallization, or chemistry. Maybe very few of the bits that drop off become good copies, so people argue that there is no permanent retention of improvements but just a permanent set of random factors.

        Doubtless, our evolution went through this stage. There was no life. Later, there was life. In between, there probably was some poorly optimized meta-life that limps along without being quite one thing or the other. Metazoologists will one day describe and classify such forms, and write learned papers.

        We learn as we go along. A few years ago, prions were just chemicals.

  2. metamaterials says:

    Star and Cell formation is associated with methanol and carbon likely as one dimensional carbon nanotubes in the galactic disk. Globules are nearby in our galaxy seen producing a blackened empty sky of opaque nebulae clouds with high methanol content is where stars are forming. Of interest is that stars are 99.9% plasma and so are living carbon cells. NASA plasma physicist says universe is 99.9% plasma. When a cell dies it suddenly explodes apart reaching million degree temps and evaporates much as the plasma supernova. Solar filaments with newer techniques get more visible and larger sized reaching earths ionsphere causing the northern lights. Cell structures like mitochondria have their own DNA and are in every cell. There are over 1,000 trillion individual cells in the human body outnumbered 10 to 1 bacterial to animal cells in symbiosis, which is 1,000 times greater then 1 trillion known seen galaxies in the observable universe. Dust forms helical structures in outer space and DNA self assembles on carbon nanotubes showed Johnson. This makes ribosomes functional equivalents to carbon nanotubes that contain metallic flourenes where buckyballs interact electromagnetically inside. Just recent evidence of meteorites shows strong evidence that DNA forms in outer space ! Non biological molecules that synthesize DNA were found in a meteorite containing DNA, which discredits the widely held earth contamination theory.

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