A search for interstellar pyrimidine

Kuan, Y. J.; Yan, C.; Charnley, Steven B.; Kisiel, Zbigniew; Ehrenfreund, P.; Huang, Hui‐Chun

doi:10.1046/j.1365-8711.2003.06975.x

Cited by 85 publications

(79 citation statements)

References 34 publications

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“…In such a cold environment rotational transitions of uracil peak in the 3 mm band and its gas phase emission spectrum might be observable, provided that an efficient formation and ejection process exists, possibly one caused by shocks. Based on these assumptions, we searched for uracil emission lines in two recent line surveys of the Sgr B2(N) region by Apponi (2006) and Belloche (2006) performed with the Kitt Peak 12 m and IRAM 30 m radio telescopes, respectively, and obtained an upper limit for the uracil column density of N = 6.0 × 10 13 cm −2 , which is only slightly less than the pyrimidine upper limit of 1.7 × 10 14 cm −2 in this source (Kuan et al 2003b). Out of the 18 lines which fall within the range of the surveys, 13 coincide with emission lines and 2 with absorption features.…”

Section: Discussionmentioning

confidence: 94%

“…The possible formation processes of nucleobases in the ISM have been discussed most recently by Peeters et al (2003Peeters et al ( , 2005. These authors suggest that the most likely formation of uracil is by photoprocessing of pyrimidine (c-C 4 H 4 N 2 ) in water-ice containing dust grains, which links the expected interstellar uracil abundance to that of pyrimidine, which has not yet been detected in the ISM (Kuan et al 2003b). The synthesis of uracil on icy dust grains may follow a similar pathway to that proposed in an aqueous environment on the prebiotic earth.…”

Section: Introductionmentioning

confidence: 99%

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Improved line frequencies for the nucleic acid base uracil for a radioastronomical search

Brünken

McCarthy

Thaddeus

et al. 2006

A&A

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Aims. We report new laboratory spectroscopic data on the rotational spectrum of the pyrimidine nucleic acid base uracil (C 4 H 4 N 2 O 2 ). The dataset has been extended both into the microwave region and towards mm-wavelengths with the aim of providing accurate transition rest frequencies for astrophysical searches. Methods. The microwave measurements have been performed with a molecular beam Fourier transform microwave spectrometer in the frequency range from 9-19 GHz and the mm-wave band transitions have been recorded with a Stark-modulated free jet spectrometer up to 100 GHz. The global dataset has been analysed with a standard S -reduced Hamiltonian and precise spectroscopic parameters up to quartic order have been obtained. The hyperfine structure due to the two 14 N nuclei has been resolved in the microwave measurements and the nuclear quadrupole coupling constants could be derived to high accuracy. Results. Based on the new laboratory data and analysis, highly precise rotational transition rest frequencies are available for astrophysical important lines of uracil up to 300 GHz.

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Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Improved line frequencies for the nucleic acid base uracil for a radioastronomical search

Brünken

McCarthy

Thaddeus

et al. 2006

A&A

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“…1 only benzene has been detected, by ISO observations in post-asymptotic giant branch (AGB) object CRL 618 (Cernicharo et al 2001). In parallel with the experimental work reported here and by Peeters et al (2003), we have undertaken an observational program to search for various N-heterocycles in interstellar and circumstellar environments (Kuan et al 2003c(Kuan et al , 2004. Searches for pyridine towards carbon-rich AGBs did not yield any positive results.…”

Section: Introductionmentioning

confidence: 85%

Formation and photostability of N-heterocycles in space

Peeters¹,

Botta

Charnley

et al. 2005

A&A

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Abstract. 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 10-100 years, while in the Solar System at 1 AU 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.

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“…Nitrogen heterocycles, including nucleobases, have been detected in a number of carbonaceous chondrites such as Murchison, Murray, Orgueil, and Lonewolf Nunataks 94102 (Folsome et al 1971;Hayatsu et al 1975;Stoks & Schwartz 1979;Callahan et al 2011), and their extraterrestrial origin is supported by isotopic measurements (Martins et al 2008). To date, no individual N-heterocycles have been detected in the gas phase of the interstellar medium (ISM) despite extensive astronomical observation efforts (Simon & Simon 1973;Kuan et al 2003;Charnley et al 2005). However, analysis of the emission features in astrophysical environments associated with polycyclic aromatic hydrocarbons (PAHs) suggests that N-heterocycles-sometimes referred to as polycyclic aromatic nitrogen heterocycles (PANHs)-may constitute part of the PAH population (Mattioda et al 2003;.…”

Section: Introductionmentioning

confidence: 99%

The Photochemistry of Pyrimidine in Realistic Astrophysical Ices and the Production of Nucleobases

Nuevo

Materese

Sandford

2014

ApJ

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Nucleobases, together with deoxyribose/ribose and phosphoric acid, are the building blocks of DNA and RNA for all known life. The presence of nucleobase-like compounds in carbonaceous chondrites delivered to the Earth raises the question of an extraterrestrial origin for the molecules that triggered life on our planet. Whether these molecules are formed in interstellar/protostellar environments, in small parent bodies in the solar system, or both, is currently unclear. Recent experiments show that the UV irradiation of pyrimidine (C 4 H 4 N 2 ) in H 2 O-rich ice mixtures that contain NH 3 , CH 3 OH, or CH 4 leads to the formation of the pyrimidine-based nucleobases uracil, cytosine, and thymine. In this work, we discuss the low-temperature UV irradiation of pyrimidine in realistic astrophysical ice mixtures containing H 2 O, CH 3 OH, and NH 3 , with or without CH 4 , to search for the production of nucleobases and other prebiotic compounds. These experiments show the presence of uracil, urea, glycerol, hexamethylenetetramine, small amino acids, and small carboxylic acids in all samples. Cytosine was only found in one sample produced from ices irradiated with a higher UV dose, while thymine was not found in any sample, even after irradiation with a higher UV dose. Results are discussed to evaluate the role of the photochemistry of pyrimidine in the inventory of organic molecules detected in meteorites and their astrophysical/astrobiological implications.

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A search for interstellar pyrimidine

Cited by 85 publications

References 34 publications

Improved line frequencies for the nucleic acid base uracil for a radioastronomical search

Improved line frequencies for the nucleic acid base uracil for a radioastronomical search

Formation and photostability of N-heterocycles in space

The Photochemistry of Pyrimidine in Realistic Astrophysical Ices and the Production of Nucleobases

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