Query : 2005A&A...433..583P

2005A&A...433..583P - Astronomy and Astrophysics, volume 433, 583-590 (2005/4-2)

Formation and photostability of N-heterocycles in space. I. The effect of nitrogen on the photostability of small aromatic molecules.


Abstract (from CDS):

Nitrogen-containing cyclic organic molecules (N-heterocycles) play important roles in terrestrial biology, for example as the nucleobases in genetic material. It has previously been shown that nucleobases are unlikely to form and survive in interstellar and circumstellar environments. Also, they were found to be unstable against ultraviolet (UV) radiation. However, nucleobases were detected in carbonaceous meteorites, suggesting their formation and survival is possible outside the Earth. In this study, the nucleobase precursor pyrimidine and the related N-heterocycles pyridine and s-triazine were tested for UV stability. All three N-heterocycles were found to photolyse rapidly and their stability decreased with an increasing number of nitrogen atoms in the ring. The laboratory results were extrapolated to astronomically relevant environments. In the diffuse interstellar medium (ISM) these N-heterocycles in the gas phase would be destroyed in 10-100years, while in the Solar System at 1AU distance from the Sun their lifetime would not extend beyond several hours. The only environment where small N-heterocycles could survive, is in dense clouds. Pyridine and pyrimidine, but not s-triazine, could survive the average lifetime of such a cloud. The regions of circumstellar envelopes where dust attenuates the UV flux, may provide a source for the detection of N-heterocycles. We conclude that these results have important consequences for the detectability of N-heterocycles in astronomical environments.

Abstract Copyright:

Journal keyword(s): astrobiology - methods: laboratory - stars: individual: CRL 618

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 RAFGL 618 pA* 04 42 53.6242032600 +36 06 53.400902220   16.32   12.59   C-rich 991 0
2 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 2228 1
3 IRC +10216 C* 09 47 57.40632 +13 16 43.5648           C9,5e 2285 0
4 NAME Sgr B2 (North) Rad 17 47 20.2 -28 22 21           ~ 636 1
5 W 51e1 HII 19 23 43.785 +14 30 26.11           ~ 129 0
6 W 51e2 PCG 19 23 43.906 +14 30 34.48           ~ 206 0

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