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Formamide in Protostellar Shocks: Evidence for Gas-phase Formation
Context: Modern versions of the Miller-Urey experiment claim that formamide (NH2CHO) could be the starting point for the formation of metabolic and genetic macromolecules.
Intriguingly, formamide is indeed observed in regions forming Solar-type stars as well as in external galaxies. Aims: How NH2CHO is formed has been a puzzle for decades: our goal is to contribute to the hotly debated question of whether formamide is mostly formed via gas-phase or grain surface chemistry. Methods: We used the NOEMA interferometer to image NH2CHO towards the L1157-B1 blue-shifted shock, a well known interstellar laboratory, to study how the components of dust mantles and cores released into the gas phase triggers the formation of formamide. Results: We report the first spatially resolved image (size ∼ 9″, ∼ 2300 AU) of formamide emission in a shocked region around a Sun-like protostar: the line profiles are blueshifted and have a FWHM ≃ 5 km s−1. A column density of NNH2CHO = 8 × 1012 cm−1, and an abundance (with respect to H-nuclei) of 4 × 10−9 are derived.
We show a spatial segregation of formamide with respect to other organic species. Our observations, coupled with a chemical modelling analysis, indicate that the formamide observed in L1157-B1 is formed by gas-phase chemical process, and not on grain surfaces as previously suggested. Conclusions: The SOLIS interferometric observations of formamide provide direct evidence that this potentially crucial brick of life is efficiently formed in the gas-phase around Sun-like protostars.
Seeds of Life in Space (SOLIS) III. Formamide in protostellar shocks: evidence for gas-phase formation
C. Codella, C. Ceccarelli, P. Caselli, N. Balucani, V. Baroneınst, F. Fontani, B. Lefloch, L. Podio, S. Viti, S. Feng, R. Bachiller, E. Bianchi, F. Dulieu, I. Jiménez-Serra, J. Holdship, R. Neri, J. Pineda, A. Pon, I. Sims, S. Spezzano, A.I. Vasyunin, F. Alves, L. Bizzocchi, S. Bottinelli, E. Caux, A. Chacón-Tanarro, R. Choudhury, A. Coutens, C. Favre, P. Hily-Blant, C. Kahane, A. Jaber Al-Edhari, J. Laas, A. López-Sepulcre, J. Ospina, Y. Oya, A. Punanova, C. Puzzarini, D. Quenard, A. Rimola, N. Sakai, D. Skouteris, V. Taquet, L. Testi, P. Theulé, P. Ugliengo, C. Vastel, F. Vazart, L. Wiesenfeld, S. Yamamoto
(Submitted on 15 Aug 2017)
Comments: 7 pages, 1 table, 5 figures, A&A Letters, in press
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1708.04663 [astro-ph.EP]
(or arXiv:1708.04663v1 [astro-ph.EP] for this version)
From: Claudio Codella
[v1] Tue, 15 Aug 2017 20:04:33 GMT (197kb)