Poster Open Access

Understanding Chemical Complexity in Protostellar Outflows L1157-B1 Star Forming Region

Kavak, U.; Viannet, T.


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{
  "publisher": "Zenodo", 
  "DOI": "10.5281/zenodo.3469667", 
  "language": "eng", 
  "title": "Understanding Chemical Complexity in Protostellar Outflows L1157-B1 Star Forming Region", 
  "issued": {
    "date-parts": [
      [
        2019, 
        10, 
        2
      ]
    ]
  }, 
  "abstract": "<p>During the early evolutionary stages of star formation, molecular outflows are&nbsp;produced by the shocked gas interaction between high-velocity jets driven by the&nbsp;protostar and the ambient material. Shocks quickly release the content of interstellar ices into the gas phase through ice sputtering and trigger a rich endothermic gas-phase chemistry. Spatially resolved molecular outflows are known to be chemically rich&nbsp;with the detection of several dozens of species and provide us a laboratory to&nbsp;test different chemical scenarios. Complex Organic Molecules (COMs), molecules based on carbon chemistry and probably at the origin of the prebiotic&nbsp;chemistry we see in our Solar System, have been routinely detected around&nbsp;protostars in large quantities. The presence of many COMs has been understood&nbsp;as due to warm surface chemistry triggered by UV photolysis. The recent&nbsp;detection of several COMs towards the protostellar outflow prototype L1157-B1 challenges our&nbsp;current understanding of the chemistry producing these COMs. The large distance of the&nbsp;source with respect to the central heating protostar (about 60 arcsec) suggests that&nbsp;the pre-shock material is too cold to efficiently produce COMs through warm surface chemistry.&nbsp;</p>\n\n<p>In this project, we theoretically studied the formation and evolution of COMs&nbsp;occurring in molecular outflows. For this purpose, the results of a state-of-the-art 1D&nbsp;physical shock model were applied to a gas-grain astrochemical model&nbsp;in order to assess whether COMs can be produced in molecular outflows through gas-phase&nbsp;chemistry. Then, the results of the model predictions were compared with recent&nbsp;observations carried out with modern sub-millimeter facilities of the prototype outflow L1157-B1.&nbsp;<br>\nIt is concluded that dimethyl ether (DME) and methyl formate (MF), the two most&nbsp;abundant COMs in star-forming regions can be produced in significant quantities in shock regions.</p>\n\n<p>The production of these COMs in shocks is mostly due to of neutral-neutral chemistry, triggered&nbsp;by the destruction of methanol through reactions involving atomic H forming the CH$_2$OH and&nbsp;CH$_3$O radicals. Nevertheless, it seems that gas-phase chemistry alone only accounts for a&nbsp;significant but not entire&nbsp;part of the observed DME and MF abundances of a few percent with&nbsp;respect to methanol. Alternative pathways, such as cold surface chemistry, for instance,&nbsp;could also play a role.</p>", 
  "author": [
    {
      "family": "Kavak, U."
    }, 
    {
      "family": "Viannet, T."
    }
  ], 
  "id": "3469667", 
  "type": "graphic", 
  "event": "FUNDAMENTALS OF LIFE IN THE UNIVERSE 2017, GRONINGEN, THE NETHERLANDS"
}
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