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15 results on '"Spezzano, S."'

1. Massive clumps in W43-main: Structure formation in an extensively shocked molecular cloud.

Author

Lin, Y., Wyrowski, F., Liu, H. B., Gong, Y., Sipilä, O., Izquierdo, A., Csengeri, T., Ginsburg, A., Li, G. X., Spezzano, S., Pineda, J. E., Leurini, S., Caselli, P., and Menten, K. M.

Subjects
MOLECULAR clouds, SHOCK waves, KINEMATICS, LEGAL evidence, GAS dynamics
Abstract

Aims. W43-main is a massive molecular complex undergoing starburst activities, located at the interaction of the Scutum arm and the Galactic bar. We aim to investigate the gas dynamics, in particular, the prevailing shock signatures from cloud to clump scales. We also look to assess the impact of shocks on the formation of dense gas and early-stage cores in OB cluster formation processes. Methods. We carried out NOEMA and IRAM-30 m observations at 3 mm towards five molecular gas clumps in W43 main located within large-scale interacting gas components. We used CH3CCH and H2CS lines to trace the extended gas temperature and CH3OH lines to probe the volume density of the dense gas components (≳105 cm−3). We adopted multiple tracers that are sensitive to different gas density regimes to reflect the global gas motions. The density enhancements constrained by CH3OH and a population of NH2D cores are correlated (in the spatial and velocity domains) with SiO emission, which is a prominent indicator of shock processing in molecular clouds. Results. The emission of SiO (2–1) is extensive across the region (~4 pc) and it is contained within a low-velocity regime, hinting at a large-scale origin for the shocks. Position-velocity maps of multiple tracers show systematic spatio-kinematic offsets supporting the cloud-cloud collision-merging scenario. We identified an additional extended velocity component in the CCH emission, which coincides with one of the velocity components of the larger scale 13CO (2−1) emission, likely representing an outer, less-dense gas layer in the cloud merging process. We find that the 'V-shaped', asymmetric SiO wings are tightly correlated with localised gas density enhancements, which is direct evidence of dense gas formation and accumulation in shocks. The dense gas that is formed in this way may facilitate the accretion of the embedded, massive pre-stellar and protostellar cores. We resolved two categories of NH2D cores: those exhibiting only subsonic to transonic velocity dispersions and those with an additional supersonic velocity dispersion. The centroid velocities of the latter cores are correlated with the shock front seen via SiO. The kinematics of the ~0.1 pc NH2D cores are heavily imprinted by shock activities and may represent a population of early-stage cores forming around the shock interface. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Similar levels of deuteration in the pre-stellar core L1544 and the protostellar core HH211

Author

Giers, K., Spezzano, S., Caselli, P., Wirström, E., Sipilä, O., Pineda, J. E., Redaelli, E., Bop, C. T., Lique, F., Max-Planck-Institut für Extraterrestrische Physik (MPE), Onsala Space Observatory (OSO), Chalmers University of Technology [Göteborg], Institut de Physique de Rennes (IPR), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
astrochemistry, radiative transfer, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Stars: formation, Astrophysics - Astrophysics of Galaxies, ISM: clouds, ISM: molecules, ISM: abundances
Abstract

In the centre of pre-stellar cores, deuterium fractionation is enhanced due to the low temperatures and high densities. Therefore, the chemistry of deuterated molecules can be used to study the earliest stages of star formation. We analyse the deuterium fractionation of simple molecules, comparing the level of deuteration in the envelopes of the pre-stellar core L1544 in Taurus and the protostellar core HH211 in Perseus. We used single-dish observations of CCH, HCN, HNC, HCO$^+$, and their $^{13}$C-, $^{18}$O- and D-bearing isotopologues, detected with the Onsala 20m telescope. We derived the column densities and the deuterium fractions of the molecules. Additionally, we used radiative transfer simulations and results from chemical modelling to reproduce the observed molecular lines. We used new collisional rate coefficients for HNC, HN$^{13}$C, DNC, and DCN that consider the hyperfine structure of these molecules. We find high levels of deuteration for CCH (10%) in both sources, consistent with other carbon chains, and moderate levels for HCN (5-7%) and HNC (8%). The deuterium fraction of HCO$^+$ is enhanced towards HH211, most likely caused by isotope-selective photodissociation of C$^{18}$O. Similar levels of deuteration show that the process is likely equally efficient towards both cores, suggesting that the protostellar envelope still retains the chemical composition of the original pre-stellar core. The fact that the two cores are embedded in different molecular clouds also suggests that environmental conditions do not have a significant effect on the deuteration within dense cores. Radiative transfer modelling shows that it is necessary to include the outer layers of the cores to consider the effects of extended structures. Besides HCO$^+$ observations, HCN observations towards L1544 also require the presence of an outer diffuse layer where the molecules are relatively abundant., Comment: 27 pages, 17 figures, accepted for publication in A&A

Published
2023
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3. The complex organic molecular content in the L1517B starless core.

Author

Megías, A, Jiménez-Serra, I, Martín-Pintado, J, Vasyunin, A I, Spezzano, S, Caselli, P, Cosentino, G, and Viti, S

Subjects
METHANOL, MOLECULES, ASTROCHEMISTRY
Abstract

Recent observations of the pre-stellar core L1544 and the younger starless core L1498 have revealed that complex organic molecules (COMs) are enhanced in the gas phase towards their outer and intermediate-density shells. Our goal is to determine the level of chemical complexity towards the starless core L1517B, which seems younger than L1498, and compare it with the other two previously studied cores to see if there is a chemical evolution within the cores. We have carried out 3 mm high-sensitivity observations towards two positions in the L1517B starless core: the core's centre and the position where the methanol emission peaks (at a distance of ∼5000 au from the core's centre). Our observations reveal that a lower number of COMs and COM precursors are detected in L1517B with respect to L1498 and L1544, and also show lower abundances. Besides methanol, we only detected CH3O, H2CCO, CH3CHO, CH3CN, CH3NC, HCCCN, and HCCNC. Their measured abundances are ∼3 times larger towards the methanol peak than towards the core's centre, mimicking the behaviour found towards the more evolved cores L1544 and L1498. We propose that the differences in the chemical complexity observed between the three studied starless cores are a consequence of their evolution, with L1517B being the less evolved one, followed by L1498 and L1544. Chemical complexity in these cores seems to increase over time, with N-bearing molecules forming first and O-bearing COMs forming at a later stage as a result of the catastrophic depletion of CO. [ABSTRACT FROM AUTHOR]

Published
2023
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4. Tracing the contraction of the pre-stellar core L1544 with HC17O+ J = 1–0 emission

Author

Asensio, J. Ferrer, Spezzano, S., Caselli, P., Alves, F. O., Sipilä, O., Redaelli, E., Bizzocchi, L., Lique, F., Mullins, A., Max-Planck-Institut für Extraterrestrische Physik (MPE), Scuola Normale Superiore di Pisa (SNS), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), and J.F.A., S.S., P.C., F.O.A., O.S, E.R. and L.B. gratefully acknowledge the support of the Max Planck Society.

Subjects
[PHYS]Physics [physics], radio lines: ISM, stars: formation, radiative transfer, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astronomy and Astrophysics, Quantum dynamics, Molecular physics, Astrophysics - Astrophysics of Galaxies, ISM: clouds, ISM: molecules
Abstract

Context. Spectral line profiles of several molecules observed towards the pre-stellar core L1544 appear double-peaked. For abundant molecular species this line morphology has been linked to self-absorption. However, the physical process behind the double-peaked morphology for less abundant species is still under debate. Aims. In order to understand the cause behind the double-peaked spectra of optically thin transitions and their link to the physical structure of pre-stellar cores, we present high-sensitivity and high spectral resolution HC17O+ J =1−0 observations towards the dust peak in L1544. Methods. We observed the HC17O+(1−0) spectrum with the Institut de Radioastronomie Millimétrique (IRAM) 30 m telescope. By using state-of-the-art collisional rate coefficients, a physical model for the core and the fractional abundance profile of HC17O+, the hyperfine structure of this molecular ion is modelled for the first time with the radiative transfer code loc applied to the predicted chemical structure of a contracting pre-stellar core. We applied the same analysis to the chemically related C17O molecule. Results. The observed HC17O+(1−0) and C17O(1−0) lines were successfully reproduced with a non-local thermal equilibrium (LTE) radiative transfer model applied to chemical model predictions for a contracting pre-stellar core. An upscaled velocity profile (by 30%) is needed to reproduce the HC17O+(1−0) observations. Conclusions. The double peaks observed in the HC17O+(1−0) hyperfine components are due to the contraction motions at densities close to the critical density of the transition (~105 cm−3) and to the decreasing HCO+ fractional abundance towards the centre.

Published
2022

5. Tracing the contraction of the pre-stellar core L1544 with HC17O+J = 1–0 emission.

Author

Ferrer Asensio, J., Spezzano, S., Caselli, P., Alves, F. O., Sipilä, O., Redaelli, E., Bizzocchi, L., Lique, F., and Mullins, A.

Subjects
*ASTROCHEMISTRY, *MASS transfer coefficients, *THERMAL equilibrium, *HYPERFINE structure, *RADIATIVE transfer, *CHEMICAL models, *IONS, *IONIC structure
Abstract

Context. Spectral line profiles of several molecules observed towards the pre-stellar core L1544 appear double-peaked. For abundant molecular species this line morphology has been linked to self-absorption. However, the physical process behind the double-peaked morphology for less abundant species is still under debate. Aims. In order to understand the cause behind the double-peaked spectra of optically thin transitions and their link to the physical structure of pre-stellar cores, we present high-sensitivity and high spectral resolution HC17O+J =1−0 observations towards the dust peak in L1544. Methods. We observed the HC17O+(1−0) spectrum with the Institut de Radioastronomie Millimétrique (IRAM) 30 m telescope. By using state-of-the-art collisional rate coefficients, a physical model for the core and the fractional abundance profile of HC17O+, the hyperfine structure of this molecular ion is modelled for the first time with the radiative transfer code loc applied to the predicted chemical structure of a contracting pre-stellar core. We applied the same analysis to the chemically related C17O molecule. Results. The observed HC17O+(1−0) and C17O(1−0) lines were successfully reproduced with a non-local thermal equilibrium (LTE) radiative transfer model applied to chemical model predictions for a contracting pre-stellar core. An upscaled velocity profile (by 30%) is needed to reproduce the HC17O+(1−0) observations. Conclusions. The double peaks observed in the HC17O+(1−0) hyperfine components are due to the contraction motions at densities close to the critical density of the transition (~105 cm−3) and to the decreasing HCO+ fractional abundance towards the centre. [ABSTRACT FROM AUTHOR]

Published
2022
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6. Efficiency of non-thermal desorptions in cold-core conditions: Testing the sputtering of grain mantles induced by cosmic rays

Author

Wakelam, V., Dartois, E., Chabot, M., Spezzano, S., Navarro-Almaida, D., Loison, J.-C., Fuente, A., Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Moléculaires (ISM), and Université Montesquieu - Bordeaux 4-Université Sciences et Technologies - Bordeaux 1-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
cosmic rays, astrochemistry, evolution, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ISM: molecules, ISM: abundances
Abstract

International audience; Context. Under cold conditions in dense cores, gas-phase molecules and atoms are depleted from the gas-phase to the surface of interstellar grains. Considering the time scales and physical conditions within these cores, a portion of these molecules has to be brought back into the gas-phase to explain their observation by milimeter telescopes.Aims. We tested the respective efficiencies of the different mechanisms commonly included in the models (photo-desorption, chemical desorption, and cosmic-ray-induced whole-grain heating). We also tested the addition of sputtering of ice grain mantles via a collision with cosmic rays in the electronic stopping power regime, leading to a localized thermal spike desorption that was measured in the laboratory.Methods. The ice sputtering induced by cosmic rays has been added to the Nautilus gas-grain model while the other processes were already present. Each of these processes were tested on a 1D physical structure determined by observations in TMC1 cold cores. We focused the discussion on the main ice components, simple molecules usually observed in cold cores (CO, CN, CS, SO, HCN, HC3N, and HCO+), and complex organic molecules (COMs such as CH3OH, CH3CHO, CH3OCH3, and HCOOCH3). The resulting 1D chemical structure was also compared to methanol gas-phase abundances observed in these cores.Results. We found that all species are not sensitive in the same way to the non-thermal desorption mechanisms, and the sensitivity also depends on the physical conditions. Thus, it is mandatory to include all of them. Chemical desorption seems to be essential in reproducing the observations for H densities smaller than 4 × 104 cm−3, whereas sputtering is essential above this density. The models are, however, systematically below the observed methanol abundances. A more efficient chemical desorption and a more efficient sputtering could better reproduce the observations.Conclusions. In conclusion, the sputtering of ices by cosmic-rays collisions may be the most efficient desorption mechanism at high density (a few 104 cm−3 under the conditions studied here) in cold cores, whereas chemical desorption is still required at smaller densities. Additional works are needed on both mechanisms to assess their efficiency with respect to the main ice composition.

Published
2021

7. Distribution of methanol and cyclopropenylidene around starless cores.

Author

Spezzano, S., Caselli, P., Pineda, J. E., Bizzocchi, L., Prudenzano, D., and Nagy, Z.

Subjects
*METHANOL, *CARBON monoxide, *STAR formation, *EARLY stars
Abstract

Context. The spatial distribution of molecules around starless cores is a powerful tool for studying the physics and chemistry governing the earliest stages of star formation. Aims. Our aim is to study the chemical differentiation in starless cores to determine the influence of large-scale effects on the spatial distribution of molecules within the cores. Furthermore, we want to put observational constraints on the mechanisms responsible in starless cores for the desorption of methanol from the surface of dust grains where it is efficiently produced. Methods. We mapped methanol, CH3OH, and cyclopropenylidene, c-C3H2, with the IRAM 30 m telescope in the 3 mm band towards six starless cores embedded in different environments, and in different evolutionary stages. Furthermore, we searched for correlations among physical properties of the cores and the methanol distribution. Results. From our maps we can infer that the chemical segregation between CH3OH and c-C3H2 is driven by uneven illumination from the interstellar radiation field (ISRF). The side of the core that is more illuminated has more C atoms in the gas-phase and the formation of carbon-chain molecules like c-C3H2 is enhanced. Instead, on the side that is less exposed to the ISRF the C atoms are mostly locked in carbon monoxide, CO, the precursor of methanol. Conclusions. We conclude that large-scale effects have a direct impact on the chemical segregation that we can observe at core scale. However, the non-thermal mechanisms responsible for the desorption of methanol in starless cores do not show any dependency on the H2 column density at the methanol peak. [ABSTRACT FROM AUTHOR]

Published
2020
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8. Seeds of Life in Space (SOLIS): VII. Discovery of a cold dense methanol blob toward the L1521F VeLLO system.

Author

Favre, C., Vastel, C., Jimenez-Serra, I., Quénard, D., Caselli, P., Ceccarelli, C., Chacón-Tanarro, A., Fontani, F., Holdship, J., Oya, Y., Punanova, A., Sakai, N., Spezzano, S., Yamamoto, S., Neri, R., López-Sepulcre, A., Alves, F., Bachiller, R., Balucani, N., and Bianchi, E.

Subjects
STELLAR evolution, METHYL formate, GAS dynamics, METHANOL, METHYL ether, CHONDROITIN sulfates, STAR formation
Abstract

Aims. The Seeds Of Life In Space IRAM/NOEMA large program aims at studying a set of crucial complex organic molecules in a sample of sources with a well-known physical structure that covers the various phases of solar-type star formation. One representative object of the transition from the prestellar core to the protostar phases has been observed toward the very low luminosity object (VeLLO) L1521F. This type of source is important to study to link prestellar cores and Class 0 sources and also to constrain the chemical evolution during the process of star formation. Methods. Two frequency windows (81.6-82.6 GHz and 96.65-97.65 GHz) were used to observe the emission from several complex organics toward the L1521F VeLLO. These setups cover transitions of ketene (H2CCO), propyne (CH3CCH), formamide (NH2CHO), methoxy (CH3O), methanol (CH3OH), dimethyl ether (CH3OCH3), and methyl formate (HCOOCH3). Results. Only two transitions of methanol (A+, E2) have been detected in the narrow window centered at 96.7 GHz (with an upper limit on E1) in a very compact emission blob (~700 corresponding to ~1000 au) toward the northeast of the L1521F protostar. The CS 2-1 transition is also detected within theWideX bandwidth. Consistently with what has been found in prestellar cores, the methanol emission appears ~1000 au away from the dust peak. The location of the methanol blob coincides with one of the filaments that have previously been reported in the literature. The excitation temperature of the gas inferred from methanol is (10 ± 2) K, while the H2 gas density (estimated from the detected CS 2-1 emission and previous CS 5-4 ALMA observations) is a factor >25 higher than the density in the surrounding environment (n(H2) 107 cm-3). Conclusions. Based on its compactness, low excitation temperature, and high gas density, we suggest that the methanol emission detected with NOEMA is (i) either a cold and dense shock-induced blob that formed recently (≤ a few hundred years) by infalling gas or (ii) a cold and dense fragment that may just have been formed as a result of the intense gas dynamics within the L1521F VeLLO system. [ABSTRACT FROM AUTHOR]

Published
2020
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9. High-sensitivity maps of molecular ions in L1544: I. Deuteration of N2H+ and HCO+ and primary evidence of N2D+ depletion.

Author

Redaelli, E., Bizzocchi, L., Caselli, P., Sipilä, O., Lattanzi, V., Giuliano, B. M., and Spezzano, S.

Subjects
IONS, DEUTERATION, DEUTERIUM, CHEMICAL models, RADIATIVE transfer, ASTROCHEMISTRY, THERMODYNAMIC equilibrium
Abstract

Context. The deuterium fraction in low-mass prestellar cores is a good diagnostic indicator of the initial phases of star formation, and is also a fundamental quantity to infer the ionisation degree in these objects. Aims. With the analysis of multiple transitions of N2H+, N2D+, HC18O+, and DCO+ we are able to determine the molecular column density maps and the deuterium fraction in N2H+ and HCO+ toward the prototypical prestellar core L1544. This is the preliminary step to derive the ionisation degree in the source. Methods. We used a non-local thermodynamic equilibrium (non-LTE) radiative transfer code combined with the molecular abundances derived from a chemical model to infer the excitation conditions of all the observed transitions. This allowed us to derive reliable maps of the column density of each molecule. The ratio between the column density of a deuterated species and its non-deuterated counterpart gives the sought-after deuteration level. Results. The non-LTE analysis confirms that, for the molecules analysed, higher-J transitions are characterised by excitation temperatures that are ≈1–2 K lower than those of the lower-J transitions. The chemical model that provides the best fit to the observational data predicts the depletion of N2H+ and to a lesser extent of N2D+ in the innermost region. The peak values for the deuterium fraction that we find are D/HN2H+ = 0.26−0.14+0.15 ${\textrm{D/H}_{\textrm{N}_2\textrm{H}^+}} = 0.26^{+0.15}_{-0.14}$ D/H N 2 H + = 0.26 − 0.14 + 0.15 and D/HHCO+=0.035−0.012+0.015 $\mathrm{\textrm{D/H}_{\textrm{HCO}^+}} = 0.035^{+0.015}_{-0.012}$ D/H HCO + = 0.035 − 0.012 + 0.015 , in good agreement with previous estimates in the source. [ABSTRACT FROM AUTHOR]

Published
2019
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10. Seeds of Life in Space (SOLIS): II. Formamide in protostellar shocks: Evidence for gas-phase formation.

Author

Codella, C., Ceccarelli, C., Caselli, P., Balucani, N., Barone, V., Fontani, F., Lefloch, B., Podio, L., Viti, S., Feng, S., Bachiller, R., Bianchi, E., Dulieu, F., Jiménez-Serra, I., Holdship, J., Neri, R., Pineda, J. E., Pon, A., Sims, I., and Spezzano, S.

Subjects
FORMAMIDE, GAS phase reactions, PROTOSTARS
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. [ABSTRACT FROM AUTHOR]

Published
2017
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11. Understanding the C3H2 cyclic-to-linear ratio in L1544.

Author

Sipilä, O., Spezzano, S., and Caselli, P.

Subjects
*CYCLOPROPENYLIDENE, *ASTROCHEMISTRY, *CHEMICAL models, *SIMULATION methods & models, *LINEAR systems
Abstract

Aims. We aim to understand the high cyclic-to-linear C3H2 ratio (32 ± 4) that has been observed toward L1544. Methods. We combined a gas-grain chemical model with a physical model for L1544 to simulate the column densities of cyclic and linear C3H2 observed toward L1544. The most important reactions for the formation and destruction of both forms of C3H2 were identified, and their relative rate coefficients were varied to find the best match to the observations. Results. We find that the ratio of the rate coefficients of C3H3++e- → C3H2+H for cyclic and linear C3H2 must be ~20 to reproduce the observations, depending on the branching ratios assumed for the C3H3++e- → C3H + H2 reaction. In current astrochemical networks it is assumed that cyclic and linear C3H2 are formed in a 1:1 ratio in the aforementioned reactions. Laboratory studies and/or theoretical calculations are needed to confirm the results of our chemical modeling, which is based on observational constraints. [ABSTRACT FROM AUTHOR]

Published
2016
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12. A 1.3 cm line survey toward Orion KL.

Author

Gong, Y., Henkel, C., Thorwirth, S., Spezzano, S., Menten, K. M., Walmsley, C. M., Wyrowski, F., Mao, R. Q., and Klein, B.

Subjects
NEBULAE, SPECTRAL lines, ASTROCHEMISTRY, RADIO lines, INTERSTELLAR medium, RADIO recombination lines, LOCAL thermodynamic equilibrium
Abstract

Context. The nearby Orion Kleinmann-Low nebula is one of the most prolific sources of molecular line emission. It has served as a benchmark for spectral line searches throughout the (sub)millimeter regime. Aims. The main goal is to systematically study the spectral characteristics of Orion KL in the λ - 1.3 cm band. Methods. We carried out a spectral line survey with the Effelsberg-100 m telescope toward Orion KL. It covers the frequency range between 17.9 GHz and 26.2 GHz, i.e., the radio "K band". We also examined ALMA maps to address the spatial origin of molecules detected by our 1.3 cm line survey. Results. In Orion KL, we find 261 spectral lines, yielding an average line density of about 32 spectral features per GHz above 3σ (a typical value of 3σ is 15 mJy). The identified lines include 164 radio recombination lines (RRLs) and 97 molecular lines. The RRLs, from hydrogen, helium, and carbon, stem from the ionized material of the Orion Nebula, part of which is covered by our beam. The molecular lines are assigned to 13 different molecular species including rare isotopologues. A total of 23 molecular transitions from species known to exist in Orion KL are detected for the first time in the interstellar medium. Non-metastable (J > K) 15NH3 transitions are detected in Orion KL for the first time. Based on the velocity information of detected lines and the ALMA images, the spatial origins of molecular emission are constrained and discussed. A narrow feature is found in SO2 (81,7-72,6), but not in other SO2 transitions, possibly suggesting the presence of a maser line. Column densities and fractional abundances relative to H2 are estimated for 12 molecules with local thermodynamic equilibrium (LTE) methods. Rotational diagrams of non-metastable 14NH3 transitions with J = K + 1 to J = K + 4 yield different results; metastable (J = K) 15NH3 is found to have a higher excitation temperature than non-metastable 15NH3, also indicating that they may trace different regions. Elemental and isotopic abundance ratios are also estimated: He/H = (8.7 ± 0.7)% derived from the ratios between helium RRLs and hydrogen RRLs; 12C/13C = 63 ± 17 from 12CH3OH/13CH3OH; 14N/15N =100 ± 51 from 14NH3/15NH3; and D/H = (8.3 ± 4.5) x 10-3 from NH2D/NH3. The dispersion of the He/H ratios derived from Hα/Heα pairs to Hδ/Heδ pairs is very small, which is consistent with theoretical predictions that the departure coefficients bn factors for hydrogen and helium are nearly identical. Based on a non-LTE code that neglects excitation by the infrared radiation field and a likelihood analysis, we find that the denser regions have lower kinetic temperature, which favors an external heating of the hot core. [ABSTRACT FROM AUTHOR]

Published
2015
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13. A 1.3 cm line survey toward IRC+10216.

Author

Gong, Y., Henkel, C., Spezzano, S., Thorwirth, S., Menten, K. M., Wyrowski, F., Mao, R. Q., and Klein, B.

Subjects
N stars, CIRCUMSTELLAR matter, RADIO interference, LOCAL thermodynamic equilibrium, SILICATES, RADIO telescopes, ASTROCHEMISTRY
Abstract

Context. IRC +10216 is the prototypical carbon star exhibiting an extended molecular circumstellar envelope. Its spectral properties are therefore the template for an entire class of objects. Aims. The main goal is to systematically study the λ ~ 1.3 cm spectral line characteristics of IRC+10216. Methods. We carried out a spectral line survey with the Effelsberg-100 m telescope toward IRC +10216. It covers the frequency range between 17.8 GHz and 26.3 GHz (K-band). Results. In the circumstellar shell of IRC+10216, we find 78 spectral lines, among which 12 remain unidentified. The identified lines are assigned to 18 different molecules and radicals. A total of 23 lines from species known to exist in this envelope are detected for the first time outside the solar system and there are additional 20 lines first detected in IRC+10216. The potential orgin of "U" lines is also discussed. Assuming local thermodynamic equilibrium (LTE), we then determine rotational temperatures and column densities of 17 detected molecules. Molecular abundances relative to H2 are also estimated. A non-LTE analysis of NH3 shows that the bulk of its emission arises from the inner envelope with a kinetic temperature of 70 ± 20 K. Evidence for NH3 emitting gas with higher kinetic temperature is also obtained, and potential abundance differences between various 13C-bearing isotopologues of HC5N are evaluated. Overall, the isotopic 12C/13C ratio is estimated to be 49 ± 9. Finally, a comparison of detected molecules in the λ ~ 1.3 cm range with the dark cloud TMC-1 indicates that silicate-bearing molecules are more predominant in IRC+10216. [ABSTRACT FROM AUTHOR]

Published
2015
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14. Seeds of Life in Space (SOLIS): VI. Chemical evolution of sulfuretted species along the outflows driven by the low-mass protostellar binary NGC 1333-IRAS4A

Author

V. Taquet, C. Codella, M. De Simone, A. López-Sepulcre, J. E. Pineda, D. Segura-Cox, C. Ceccarelli, P. Caselli, A. Gusdorf, M. V. Persson, F. Alves, E. Caux, C. Favre, F. Fontani, R. Neri, Y. Oya, N. Sakai, C. Vastel, S. Yamamoto, R. Bachiller, N. Balucani, E. Bianchi, L. Bizzocchi, A. Chacón-Tanarro, F. Dulieu, J. Enrique-Romero, S. Feng, J. Holdship, B. Lefloch, A. Jaber Al-Edhari, I. Jiménez-Serra, C. Kahane, V. Lattanzi, J. Ospina-Zamudio, L. Podio, A. Punanova, A. Rimola, I. R. Sims, S. Spezzano, L. Testi, P. Theulé, P. Ugliengo, A. I. Vasyunin, F. Vazart, S. Viti, A. Witzel, Istituto Nazionale di Astrofisica (INAF), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Chalmers University of Technology [Göteborg], Centre National d'Études Spatiales [Toulouse] (CNES), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut de RadioAstronomie Millimétrique (IRAM), Centre National de la Recherche Scientifique (CNRS), The University of Tokyo (UTokyo), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Instituto Geografico Nacional (IGN), National Astronomical Observatories [Beijing] (NAOC), Chinese Academy of Sciences [Beijing] (CAS), University College of London [London] (UCL), Spanish National Research Council (CSIC), Ural Federal University [Ekaterinburg] (UrFU), Departament de Química [Barcelona] (UAB), Universitat Autònoma de Barcelona (UAB), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory (ESO), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), IRAM PdBI/NOEMA Interferometer [V05B, V010, U003, L15AA], MPG (Germany)Max Planck Society, IGN (Spain), European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grantEuropean Union (EU) [664931], PRIN-INAF 2016 'The Cradle of Life -GENESIS-SKA (General Conditions in Early Planetary Systems for the rise of life with SKA)', European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programmeEuropean Research Council (ERC) [741002], European MARIE SKLODOWSKA-CURIE ACTIONS under the European Union's Horizon 2020 research and innovation programme [811312], French National Research Agency of the 'Origin of Life' project of the Universite Grenoble-AlpesFrench National Research Agency (ANR) [ANR-15-IDEX-02], INSU/CNRS (France)Centre National de la Recherche Scientifique (CNRS), Ceccarelli, C. [0000-0001-9664-6292], Balucani, N. [0000-0001-5121-5683], Rimola, A. [0000-0002-9637-4554], Al Edhari, A. J. [0000-0003-4089-841X], De Oliveira Alves, F. [0000-0002-7945-064X], Lefloch, B. [0000-0002-9397-3826], Persson, M. V. [0000-0002-1100-5734], Bachiller, R. [0000-0002-5331-5386], Pineda, J. [0000-0002-3972-1978], Segura Cox, D. [0000-0003-3172-6763], IRAM PdBI/NOEMA Interferometer, V05B V010 U003 L15AA, Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino = University of Turin (UNITO), ANR-15-IDEX-0002,UGA,IDEX UGA(2015), Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737, Agence Nationale de la Recherche (ANR), European Research Council (ERC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), Taquet V., Codella C., De Simone M., Lopez-Sepulcre A., Pineda J.E., Segura-Cox D., Ceccarelli C., Caselli P., Gusdorf A., Persson M.V., Alves F., Caux E., Favre C., Fontani F., Neri R., Oya Y., Sakai N., Vastel C., Yamamoto S., Bachiller R., Balucani N., Bianchi E., Bizzocchi L., Chacon-Tanarro A., Dulieu F., Enrique-Romero J., Feng S., Holdship J., Lefloch B., Jaber Al-Edhari A., Jimenez-Serra I., Kahane C., Lattanzi V., Ospina-Zamudio J., Podio L., Punanova A., Rimola A., Sims I.R., Spezzano S., Testi L., Theule P., Ugliengo P., Vasyunin A.I., Vazart F., Viti S., and Witzel A.

Subjects
MILLIMETER ARRAYS, Binary number, CHEMICAL EVOLUTION, ISM: molecule, Astrophysics, Space (mathematics), 01 natural sciences, ISM: abundances, CHEMICAL CONDITIONS, ISM jets and outflows, ABUNDANCES [ISM], jets and outflows -ISM, CHEMICAL DIFFERENTIATION, 010303 astronomy & astrophysics, ISM abundances, Astrochemistry, Physics, [PHYS]Physics [physics], ASTROCHEMISTRY, Shock (fluid dynamics), INTERSTELLAR ICE, SUBMILLIMETRE TELESCOPES, NGC 1333-IRAS4A, ISM: abundance, ISM: molecules, stars formation, Radial velocity, ISM: jets and outflows, ISM individual objects NGC1333-IRAS4A, ISM: individual objects: NGC 1333-IRAS4A, CHEMICAL HISTORY, Low Mass, molecules -stars, Stars: formation, individual objects, JETS AND OUTFLOWS [ISM], FOS: Physical sciences, Context (language use), INDIVIDUAL OBJECTS: NGC 1333-IRAS4A [ISM], SILICON COMPOUNDS, SULFUR DIOXIDE, ISM molecules, astrochemistry -ISM, FORMATION [STARS], 0103 physical sciences, Protostar, ISM: jets and outflow, formation -ISM, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, abundances -ISM, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), MOLECULES [ISM], Outflow, MOLECULAR OUTFLOWS, STARS
Abstract

Context. Low-mass protostars drive powerful molecular outflows that can be observed with millimetre and submillimetre telescopes. Various sulfuretted species are known to be bright in shocks and could be used to infer the physical and chemical conditions throughout the observed outflows. Aims. The evolution of sulfur chemistry is studied along the outflows driven by the NGC 1333-IRAS4A protobinary system located in the Perseus cloud to constrain the physical and chemical processes at work in shocks. Methods. We observed various transitions from OCS, CS, SO, and SO2 towards NGC 1333-IRAS4A in the 1.3, 2, and 3 mm bands using the IRAM NOrthern Extended Millimeter Array and we interpreted the observations through the use of the Paris-Durham shock model. Results. The targeted species clearly show different spatial emission along the two outflows driven by IRAS4A. OCS is brighter on small and large scales along the south outflow driven by IRAS4A1, whereas SO2 is detected rather along the outflow driven by IRAS4A2 that is extended along the north east-south west direction. SO is detected at extremely high radial velocity up to + 25 km s-1 relative to the source velocity, clearly allowing us to distinguish the two outflows on small scales. Column density ratio maps estimated from a rotational diagram analysis allowed us to confirm a clear gradient of the OCS/SO2 column density ratio between the IRAS4A1 and IRAS4A2 outflows. Analysis assuming non Local Thermodynamic Equilibrium of four SO2 transitions towards several SiO emission peaks suggests that the observed gas should be associated with densities higher than 105 cm-3 and relatively warm (T > 100 K) temperatures in most cases. Conclusions. The observed chemical differentiation between the two outflows of the IRAS4A system could be explained by a different chemical history. The outflow driven by IRAS4A1 is likely younger and more enriched in species initially formed in interstellar ices, such as OCS, and recently sputtered into the shock gas. In contrast, the longer and likely older outflow triggered by IRAS4A2 is more enriched in species that have a gas phase origin, such as SO2., With funding from the Spanish government through the "María de Maeztu Unit of Excellence" accreditation (MDM-2017-0737)

Published
2020

15. Seeds of Life in Space (SOLIS). II. Formamide in protostellar shocks: Evidence for gas-phase formation

Author

Izaskun Jiménez-Serra, Ana Chacón-Tanarro, Claudine Kahane, Andy Pon, R. Neri, Yoko Oya, Patrice Theulé, Leonardo Testi, Audrey Coutens, Paola Caselli, Charlotte Vastel, Serena Viti, François Dulieu, Jaime E. Pineda, R. Choudhury, P. Hily-Blant, J. Ospina, Fanny Vazart, Vincenzo Barone, Ana López-Sepulcre, Ian R. Sims, Laurent Wiesenfeld, Claudio Codella, Anna Punanova, Sandrine Bottinelli, Vianney Taquet, Francesco Fontani, Jacob C. Laas, A. Jaber Al-Edhari, Linda Podio, Cecilia Ceccarelli, Satoshi Yamamoto, Nami Sakai, Felipe O. Alves, Rafael Bachiller, Emmanuel Caux, S. Spezzano, D. Quénard, Nadia Balucani, Siyi Feng, Cécile Favre, Luca Bizzocchi, Cristina Puzzarini, Bertrand Lefloch, Piero Ugliengo, Anton Vasyunin, Jonathan Holdship, Dimitrios Skouteris, Albert Rimola, E. Bianchi, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Università degli Studi di Perugia (UNIPG), INAF - Osservatorio Astronomico di Brera (OAB), Southern University of Science and Technology [Shenzhen] (SUSTech), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Queen Mary University of London (QMUL), University College of London [London] (UCL), ESAB, Universitad polytecnica de Cataluna, University of Western Ontario (UWO), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), departament de Quimica, Universitat Autònoma de Barcelona [Barcelona] (UAB), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Scuola Normale Superiore di Pisa (SNS), European Southern Observatory (ESO), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), Codella, C., Ceccarelli, C., Caselli, P., Balucani, N., Barone, V., Fontani, F., Lefloch, B., Podio, L., 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., Taquet, V., Testi, L., Theulé, P., Ugliengo, P., Vastel, C., Vazart, F., Wiesenfeld, L., Yamamoto, S., Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Perugia = University of Perugia (UNIPG), Southern University of Science and Technology (SUSTech), LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universitat Autònoma de Barcelona (UAB), Università degli studi di Torino = University of Turin (UNITO), Pineda, J. E., Vasyunin, A. I., Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)

Subjects
Formamide, Abundance (chemistry), Direct evidence, Stars: formation, FOS: Physical sciences, Context (language use), Astrophysics, ISM: molecule, 01 natural sciences, chemistry.chemical_compound, 0103 physical sciences, Protostar, molecule [ISM], 010303 astronomy & astrophysics, ISM: jets and outflow, formation [Stars], ComputingMilieux_MISCELLANEOUS, Line (formation), Earth and Planetary Astrophysics (astro-ph.EP), ISM: individual objects: L1157-B1, ISM: jets and outflows, ISM: molecules, Astronomy and Astrophysics, Space and Planetary Science, Physics, [PHYS]Physics [physics], 010308 nuclear & particles physics, jets and outflow [ISM], individual objects: L1157-B1 [ISM], Astronomy and Astrophysic, Stars, chemistry, Millimeter, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract

Context: Modern versions of the Miller-Urey experiment claim that formamide (NH$_2$CHO) 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 NH$_2$CHO 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 NH$_2$CHO 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 $\sim$ 9", $\sim$ 2300 AU) of formamide emission in a shocked region around a Sun-like protostar: the line profiles are blueshifted and have a FWHM $\simeq$ 5 km s$^{-1}$. A column density of $N_{\rm NH_2CHO}$ = 8 $\times$ 10$^{12}$ cm$^{-1}$, and an abundance (with respect to H-nuclei) of 4 $\times$ 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., 7 pages, 1 table, 5 figures, A&A Letters, in press

Published
2017

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