Seeds of Life in Space (SOLIS). II. Formamide in protostellar shocks: Evidence for gas-phase formation
Journal
Date Issued
2017
Author(s)
•
Ceccarelli, C.
•
Caselli, P.
•
Balucani, N.
•
Barone, V.
•
•
Lefloch, B.
•
•
Viti, S.
•
Feng, S.
•
Bachiller, R.
•
Bianchi, E.
•
Dulieu, F.
•
Jiménez-Serra, I.
•
Holdship, J.
•
Neri, R.
•
Pineda, J. E.
•
Pon, A.
•
Sims, I.
•
Spezzano, S.
•
Vasyunin, A. I.
•
Alves, F.
•
Bizzocchi, L.
•
Bottinelli, S.
•
Caux, E.
•
Chacón-Tanarro, A.
•
Choudhury, R.
•
Coutens, A.
•
Favre, C.
•
Hily-Blant, P.
•
Kahane, C.
•
Jaber Al-Edhari, A.
•
Laas, J.
•
López-Sepulcre, A.
•
Ospina, J.
•
Oya, Y.
•
Punanova, A.
•
Puzzarini, C.
•
Quenard, D.
•
Rimola, A.
•
Sakai, N.
•
Skouteris, D.
•
•
•
Theulé, P.
•
Ugliengo, P.
•
Vastel, C.
•
Vazart, F.
•
Wiesenfeld, L.
•
Yamamoto, S.
Abstract
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 and 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 NOrthern Extended Millimeter Array (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 a gas-phase chemical process and not on grain surfaces as previously suggested.
Conclusions: The Seeds of Life in Space (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.
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 NOrthern Extended Millimeter Array (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 a gas-phase chemical process and not on grain surfaces as previously suggested.
Conclusions: The Seeds of Life in Space (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.
The reduced datacube is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/L3
Volume
605
Start page
L3
Issn Identifier
0004-6361
Ads BibCode
2017A&A...605L...3C
Rights
open.access
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