MSGID: 1:317/3 63e1d3f1   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    A star is born: Study reveals complex chemistry inside 'stellar   
   nurseries'    
      
     Date:   
         February 6, 2023   
     Source:   
         University of Colorado at Boulder   
     Summary:   
         The universe's carbon atoms complete a journey that spans eons   
         -- forming in the hearts of dying stars, then becoming a part of   
         planets and even living organisms. Now, a team has uncovered the   
         chemistry behind one tiny, but critical, step in this process.   
      
      
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   FULL STORY   
   ==========================================================================   
   An international team of researchers has uncovered what might be a   
   critical step in the chemical evolution of molecules in cosmic "stellar   
   nurseries." In these vast clouds of cold gas and dust in space, trillions   
   of molecules swirl together over millions of years. The collapse of these   
   interstellar clouds eventually gives rise to young stars and planets.   
      
      
   ==========================================================================   
   Like human bodies, stellar nurseries contain a lot of organic molecules,   
   which are made up mostly of carbon and hydrogen atoms. The group's   
   results, published Feb. 6 in the journal Nature Astronomy, reveal how   
   certain large organic molecules may form inside these clouds. It's one   
   tiny step in the eons-long chemical journey that carbon atoms undergo --   
   forming in the hearts of dying stars, then becoming part of planets,   
   living organisms on Earth and perhaps beyond.   
      
   "In these cold molecular clouds, you're creating the first building blocks   
   that will, in the end, form stars and planets," said Jordy Bouwman,   
   research associate at the Laboratory for Atmospheric and Space Physics   
   (LASP) and assistant professor in the Department of Chemistry at the   
   University of Colorado Boulder.   
      
   For the new study, Bouwman and his colleagues took a deep dive into one   
   stellar nursery in particular: the Taurus Molecular Cloud (TMC-1). This   
   region sits in the constellation Taurus and is roughly 440 light years   
   (more than 2 quadrillion miles) from Earth. This chemically complex   
   environment is an example of what astronomers call an "accreting starless   
   core." Its cloud has begun to collapse, but scientists haven't yet   
   detected embryonic stars emerging inside it.   
      
   The team's findings hinge on a deceptively simple molecule called ortho-   
   benzyne. Drawing on experiments on Earth and computer simulations, the   
   researchers showed that this molecule can readily combine with others   
   in space to form a wide range of larger organic molecules.   
      
   Small building blocks, in other words, become big building blocks.   
      
   And, Bouwman said, those reactions could be a sign that stellar nurseries   
   are a lot more interesting than scientists give them credit for.   
      
   "We're only at the start of truly understanding how we go from these   
   small building blocks to larger molecules," he said. "I think we'll   
   find that this chemistry is so much more complex than we thought, even   
   at the earliest stages of star formation."  Fateful observation Bouwman   
   is a cosmochemist, studying a field that blends chemistry and astronomy   
   to understand the churning chemical reactions that happen deep in space.   
      
   On the surface, he said, cold molecular clouds might not seem like a   
   hotbed of chemical activity. As their name suggests, these galactic   
   primordial soups tend to be frigid, often hovering around -263 degrees   
   Celsius (about -440 degrees Fahrenheit), just 10 degrees above absolute   
   zero. Most reactions need at least a little bit of heat to get a   
   kick-start.   
      
   But cold or not, complex chemistry seems to be happening in stellar   
   nurseries.   
      
   TMC-1, in particular, contains surprising concentrations of relatively   
   large organic molecules with names like fulvenallene and 1- and 2-   
   ethynylcyclopentadiene. Chemists call them "five-membered ring compounds"   
   because they each contain a ring of carbon atoms shaped like a pentagon.   
      
   "Researchers kept detecting these molecules in TMC-1, but their origin   
   was unclear," Bouwman said.   
      
   Now, he and his colleagues think they have an answer.   
      
   In 2021, researchers using the Yebes 40-metre Radiotelescope in Spain   
   found an unexpected molecule hiding in the clouds of gas of TMC-1:   
   ortho-benzyne.   
      
   Bouwman explained that this small molecule, made up of a ring of six   
   carbon atoms with four hydrogens, is one of the extroverts of the   
   chemistry world. It easily interacts with a number of other molecules   
   and doesn't require a lot of heat to do so.   
      
   "There's no barrier to reaction," Bouwman said. "That means that it   
   has the potential to drive complex chemistry in cold environments."   
   Identifying the culprit To find out what kind of complex chemistry was   
   happening in TMC-1, Bouwman and his colleagues -- who hail from the United   
   States, Germany, the Netherlands and Switzerland -- turned to a technique   
   called "photoelectron photoion coincidence spectroscopy." The team used   
   light generated by a giant facility called a synchrotron light source to   
   identify the products of chemical reactions. They saw that ortho-benzyne   
   and methyl radicals, another common constituent of molecular clouds,   
   readily combine to form larger and more complex organic compounds.   
      
   "We knew we were onto something good," Bouwman said.   
      
   The team then drew on computer models to explore the role of ortho-benzyne   
   in a stellar nursery spread out over several light years deep in   
   space. The results were promising: The models generated clouds of gas   
   containing roughly the same mix of organic molecules that astronomers   
   had observed in TMC-1 using telescopes.   
      
   Ortho-benzyne, in other words, seems to be a prime candidate for   
   driving the gas-phase organic chemistry that occurs within these stellar   
   nurseries, Bouwman said.   
      
   He added that scientists still have a lot of work to do to fully   
   understand all the reactions happening in TMC-1. He wants to examine,   
   for example, how organic molecules in space also pick up nitrogen atoms --   
   key components of the DNA and amino acids of living organisms on Earth.   
      
   "Our findings may just change the view on what ingredients we have in   
   the first place to form new stars and new planets," Bouwman said.   
      
   Co-authors on the new paper include researchers at Leiden University   
   in the Netherlands, Benedictine College in the U.S., the University of   
   Wu"rzburg in Germany and Paul Scherrer Institute in Switzerland.   
      
       * RELATED_TOPICS   
             o Space_&_Time   
                   # Astrophysics # Stars # Galaxies # Extrasolar_Planets #   
                   Solar_Flare # Astronomy # Space_Exploration # Black_Holes   
       * RELATED_TERMS   
             o Atom o Nucleosynthesis o Definition_of_planet   
             o Extrasolar_planet o Planetary_habitability   
             o Cosmic_microwave_background_radiation o   
             Galaxy_formation_and_evolution o Extraterrestrial_life   
      
   ==========================================================================   
   Story Source: Materials provided by   
   University_of_Colorado_at_Boulder. Original written by Daniel   
   Strain. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Jordy Bouwman, Morgan N. McCabe, Christopher N. Shingledecker,   
      Joseph   
         Wandishin, Virginia Jarvis, Engelbert Reusch, Patrick Hemberger,   
         Andras Bodi. Five-membered ring compounds from the ortho-benzyne   
         + methyl radical reaction under interstellar conditions. Nature   
         Astronomy, 2023; DOI: 10.1038/s41550-023-01893-2   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230206130630.htm   
      
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