Examinando por Autor "Bizzocchi, L."

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Acceso Abierto
Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and its first detection in the ISM
(EDP Sciences, 2020-08-20) Bizzocchi, L.; Prudenzano, D.; Rivilla, V. M.; Pietropolli Charmet, A.; Giuliano, B. M.; Caselli, P.; Martín Pintado, J.; Jiménez Serra, I.; Martín, S.; Requena Torres, M. A.; Rico Villas, F.; Guillemin, J. C.; Centre National D'Etudes Spatiales (CNES); European Research Council (ERC); Agencia Estatal de Investigación (AEI); Rico Villas, F. [0000-0002-5351-3497]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Small imines containing up to three carbon atoms are present in the interstellar medium (ISM). As alkynyl compounds are abundant in this medium, propargylimine (2-propyn-1-imine, HC ≡C−CH =NH) thus represents a promising candidate for a new interstellar detection. Aims. The goal of the present work is to perform a comprehensive laboratory investigation of the rotational spectrum of propargylimine in its ground vibrational state in order to obtain a highly precise set of rest frequencies and to search for it in space. Methods. The rotational spectra of E and Z geometrical isomers of propargylimine have been recorded in the laboratory in the 83–500 GHz frequency interval. The measurements have been performed using a source-modulation millimetre-wave spectrometer equipped with a pyrolysis system for the production of unstable species. High-level ab initio calculations were performed to assist the analysis and to obtain reliable estimates for an extended set of spectroscopic quantities. We searched for propargylimine at 3 mm and 2 mm in the spectral survey of the quiescent giant molecular cloud G+0.693-0.027 located in the central molecular zone, close to the Galactic centre. Results. About 1000 rotational transitions have been recorded for the E- and Z-propargylimine, in the laboratory. These new data have enabled the determination of a very accurate set of spectroscopic parameters including rotational, quartic, and sextic centrifugal distortion constants. The improved spectral data allowed us to perform a successful search for this new imine in the G+0.693-0.027 molecular cloud. Eighteen lines of Z-propargylimine were detected at level >2.5σ, resulting in a column-density estimate of N = (0.24 ± 0.02) × 1014 cm−2. An upper limit was retrieved for the higher energy E isomer, which was not detected in the data. The fractional abundance (with respect to H2) derived for Z-propargylimine is 1.8 × 10−10. We discuss the possible formation routes by comparing the derived abundance with those measured in the source for possible chemical precursors.
Acceso Abierto
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
(EDP Sciences, 2020-05-15) Taquet, V.; Codella, C.; De Simone, M.; López 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.; Chacón Tanarro, A.; Dulieu, F.; Enrique Romero, J.; Feng, S.; Holdship, J.; Lefloch, B.; Al Edhari, A. J.; Jiménez Serra, I.; Kahane, C.; Lattanzi, V.; Ospina Zamudio, J.; Podio, L.; Punanova, A.; Rimola, A.; Sims, I. R.; Spezzano, S.; Testi, L.; Theulé, P.; Ugliengo, P.; Vasyunin, A. I.; Vazart, F.; Viti, S.; Witzel, A.; Agence Nationale de la Recherche (ANR); European Research Council (ERC); 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]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
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.
Acceso Abierto
Seeds of Life in Space (SOLIS) VII. Discovery of a cold dense methanol blob toward the L1521F VeLLO system.
(EDP Sciences, 2020-04-02) Favre, C.; Vastel, C.; Jiménez Serra, I.; Quénard, D.; Caselli, P.; Ceccarelli, C.; Chacón Tanarro, A.; Fontani, F.; Holdship, J.; Oya, Y.; Punanova, A.; Saki, N.; Spezzano, S.; Yamamoto, S.; Neri, R.; López Sepulcre, A.; Alves, F.; Bachiller, R.; Balucani, N.; Bianchi, E.; Bizzocchi, L.; Codella, C.; Caux, E.; De Simone, M.; Enrique Romero, J.; Dulieu, F.; Feng, S.; Al Edhari, A. J.; Lefloch, B.; Ospina Zamudio, J.; Pineda, J.; Podio, L.; Rimola, A.; Segura Cox, D.; Sims, I. R.; Taquet, V.; Testi, L.; Theulé, P.; Ugliengo, P.; Vasyunin, A. I.; Vazart, F.; Viti, S.; Witzel, A.; Agence Nationale de la Recherche (ANR); Spanish FEDER; Russian Science Foundation (RSF); European Research Council (ERC); Agencia Estatal de Investigación (AEI); Al Edhari, A. J. [0000-0003-4089-841X]; Rimola, A. [0000-0002-9637-4554]; Balucani, N. [0000-0001-5121-5683]; Ceccarelli, C. [0000-0001-9664-6292]; De Oliveira Alves, F. [0000-0002-7945-064X]; Pineda, J. E. [0000-0002-3972-1978]; Segura Cox, D. [0000-0003-3172-6763]; Bachiller, R. [0000-0002-5331-5386]; Fontani, F. [0000-0003-0348-3418]; Sakai, N. [0000-0002-3297-4497]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
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 (~7′′ corresponding to ~1000 au) toward the northeast of the L1521F protostar. The CS 2–1 transition is also detected within the WideX 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.