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Exploring the origins of carbon in terrestrial worlds

Bergin, Edwin A. and Cleeves, L. Ilsedore and Crockett, Nathan and Blake, Geoffrey A. (2014) Exploring the origins of carbon in terrestrial worlds. Faraday Discussions, 168 . pp. 61-79. ISSN 1359-6640.

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Given the central role of carbon in the chemistry of life, it is a fundamental question as to how carbon is supplied to the Earth, in what form and when. We provide an accounting of carbon found in solar system bodies, and in particular a comparison between the organic content of meteorites and that in identified organics in the dense interstellar medium (ISM). Based on this accounting, identified organics created by the chemistry of star formation could contain at most ~15% of the organic carbon content in primitive meteorites and significantly less for cometary organics, which represent the putative contributors to starting materials for the Earth. In the ISM ~30% of the elemental carbon exists as CO, either in gaseous form or in ices, with a typical abundance of ~10^(−4) (relative to H_2). Recent observations of the TW Hya disk find that the gas phase abundance of CO is reduced by an order of magnitude compared to this value. We explore an explanation for this observation whereby the volatile CO is destroyed via gas phase processes, providing an additional source of carbon for organic material to be incorporated into planetesimals and cometesimals. This chemical processing mechanism requires warm grains (>20 K), partially ionized gas, and sufficiently small (a_(grain) < 10μm) grains, i.e. a larger total grain surface area, such that freeze-out is efficient. Under these conditions, static (non-turbulent) chemical models predict that a large fraction of the carbon nominally sequestered in CO can be the source of carbon for a wide variety of organics that are present as ice coatings on the surfaces of warm pre-planetesimal dust grains.

Item Type:Article
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URLURL TypeDescription
Bergin, Edwin A.0000-0003-4179-6394
Cleeves, L. Ilsedore0000-0003-2076-8001
Crockett, Nathan0000-0002-6586-7591
Blake, Geoffrey A.0000-0003-0787-1610
Additional Information:© 2014 Royal Society of Chemistry. Received 16th January 2014, Accepted 12th February 2014. This work was supported by funding from the National Science Foundation grant AST-1008800 and AST-1344133 (INSPIRE). This article is part of themed collection: Astrochemistry of Dust, Ice and Gas.
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Record Number:CaltechAUTHORS:20140918-105138633
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Official Citation:Bergin, E., Ilsedore Cleeves, L., Crockett, N., & Blake, G. (2014). Exploring the origins of carbon in terrestrial worlds. [10.1039/C4FD00003J]. Faraday Discussions, 168(0), 61-79. doi: 10.1039/c4fd00003j
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49818
Deposited By: Jason Perez
Deposited On:19 Sep 2014 18:58
Last Modified:09 Mar 2020 13:18

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