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The chemical inventory of pre/proto-stellar cores

AuthorsMarcelino, Nuria ; Cernicharo, José ; Roueff, Evelyne; Gerin, Maryvonee; Fuente, Asunción
Issue Date2014
PublisherAmerican Astronomical Society
CitationAAS Meeting #223 (2014)
AbstractCold dark clouds are the sites of low-mass star formation and future planetary systems. The lack of internal heating sources and violent physical processes, like shocks, make these dense and quiescent cores the best sites to explore and to model interstellar gas-phase chemistry and molecular depletion into the dust grain surfaces. However, they have been found to be less chemically simple than previously thought. A previous limited scan between 86-93 GHz toward four dense cores demonstrated spectral line surveys are the best tool to provide a complete view of their molecular complexity. Indeed, three new molecular species were detected for the first time in space (D2CS, CH2CHCH3, and HCNO), which have become an important piece of information for chemical models. Furthermore, unexpected species can provide new information about the physical and chemical evolution of molecular cores toward star formation and complement the usual tracers. Motivated by the results of this pioneering study and the recent upgrades at the IRAM 30m, providing higher sensitivity and larger instantaneous bandwidth, we performed a survey of the whole 3mm band (82.5-117.5 GHz) toward two of the cores previously observed: B1-b in Perseus and TMC-1 in Taurus. Cernicharo et al. (2012) presented the first results from this survey including new and unexpected detections in B1-b: the discovery of the methoxy radical (CH3O) and the observation of other complex molecular species (COMs). The presence of such complex species is surprising and challenge current chemical models, since they are usually observed in hot core and corinos, where the high temperatures (>100 K) allow the evaporation of ice-mantle species. Here we present the results of the full 35 GHz scan in B1-b. So far, we have detected 325 lines from 109 molecular species and isotopomers. A total of 190 lines remain unidentified. We will show the obtained abundances and compare the results of particular species in both sources, like COMs which are not detected in TMC-1. The different chemical composition observed could be characteristic of the cloud (carbon or oxygen rich environment, presence of UV photons, etc.), but it could also be the result of very early star formation activity.
DescriptionPaper presented at the American Astronomical Society Meeting #223 that took place in Washington, DC (United States) during January 2014.
Appears in Collections:(CAB) Comunicaciones congresos
(ICMM) Comunicaciones congresos
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