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Formation of Nucleobases from the UV Irradiation of Pyrimidine in Astrophysical Ice AnalogsNucleobases are the informational subunits of DNA and RNA. They consist of Nheterocycles that belong to either the pyrimidine-base group (uracil, cytosine, and thymine) or the purinebase group (adenine and guanine). Several nucleobases, mostly purine bases, have been detected in meteorites [1-3], with isotopic signatures consistent with an extraterrestrial origin [4]. Uracil is the only pyrimidine-base compound formally reported in meteorites [2], though the presence of cytosine cannot be ruled out [5,6]. However, the actual process by which the uracil was made and the reasons for the non-detection of thymine in meteorites have yet to be fully explained. Although no N-heterocycles have ever been observed in the ISM [7,8], the positions of the 6.2-μm interstellar emission features suggest a population of such molecules is likely to be present [9]. In this work we study the formation of pyrimidine-based molecules, including the three nucleobases uracil, cytosine, and thymine from the ultraviolet (UV) irradiation of pyrimidine in ices consisting of several combinations of H(sub2)O, NH(sub3), CH(sub3)OH, and CH(sub4) at low temperature, in order to simulate the astrophysical conditions under which prebiotic species may be formed in the interstellar medium, in the protosolar nebula, and on icy bodies of the Solar System.
Document ID
20140006936
Document Type
Conference Paper
Authors
Sandford, Scott A. (NASA Ames Research Center Moffett Field, CA United States)
Nuevo, Michel (Bay Area Environmental Research Inst. Sonoma, CA, United States)
Materese, Christopher K. (NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
June 9, 2014
Publication Date
March 17, 2014
Subject Category
Astrophysics
Report/Patent Number
ARC-E-DAA-TN12718
Meeting Information
Lunar and Planetary Science Conference(Houston, TX)
Funding Number(s)
CONTRACT_GRANT: NNX12AB89A
CONTRACT_GRANT: NNH06CC03B
WBS: WBS 811073.02.07.03.55
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
UV Irradiation
Ice Irradiation
Extraterrestrial Abiotic Nucleobase Synthesis
Nucleobases
Astrochemistry

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