Examinando por Autor "Pineda, Jaime E."

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FAUST I. The hot corino at the heart of the prototypical Class I protostar L1551 IRS5.
(Oxford Academics: Oxford University Press, 2020-07-21) Bianchi, S.; Chandler, C. J.; Ceccarelli, C.; Codella, C.; Sakai, N.; López Sepulcre, A.; Maud, L. T.; Moellenbrock, G.; Svoboda, B.; Watanabe, Y.; Sakai, T.; Ménard, F.; Aikawa, Y.; Alves, F.; Balucani, N.; Bouvier, M.; Caselli, P.; Caux, E.; Charnley, S.; Choudhury, S.; De Simone, M.; Dulieu, F.; Durán, A.; Evans, L.; Favre, C.; Fedele, D.; Feng, S.; Fontani, F.; Francis, L.; Hama, T.; Hanawa, T.; Herbst, E.; Hirota, T.; Imai, M.; Isella, A.; Jiménez Serra, I.; Johnstone, D.; Kahane, C.; Lefloch, B.; Loinard, L.; Maureira, M. J.; Mercimek, S.; Miotello, A.; Mori, S.; Nakatani, R.; Nomura, H.; Oba, Y.; Ohashi, S.; Okoda, Y.; Ospina Zamudio, J.; Oya, Y.; Pineda, Jaime E.; Podio, L.; Rimola, A.; Segura Cox, D.; Shirley, Y.; Taquet, V.; Testi, L.; Vastel, C.; Viti, S.; Watanabe, N.; Witzel, A.; Xue, C.; Zhao, B.; Zhang, Y.; Yamamoto, S.; European Research Council (ERC); Japan Society for the Promotion of Science (KAKENHI); Agencia Estatal de Investigación (AEI); Universidad Nacional Autónoma de México (UNAM); Agence Nationale de la Recherche (ANR); Balucani, N. [0000-0001-5121-5683]; De Oliveira Alves, F. [0000-0002-7945-064X]; Hama, T. [0000-0002-4991-4044]; Ohashi, S. [0000-0002-9661-7958]; Johnstone, D. [0000-0002-6773-459X]; Watanabe, Y. [0000-0002-9668-3592]; Ceccarelli, C. [0000-0001-9664-6292]; Pineda, J. [0000-0002-3972-1978]; Fedele, D. [0000-0001-6156-0034]; Mercimek, S. [0000-0002-0742-7934]; Xue, C. [0000-0003-2760-2119]; 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
The study of hot corinos in solar-like protostars has been so far mostly limited to the Class 0 phase, hampering our understanding of their origin and evolution. In addition, recent evidence suggests that planet formation starts already during Class I phase, which therefore represents a crucial step in the future planetary system chemical composition. Hence, the study of hot corinos in Class I protostars has become of paramount importance. Here, we report the discovery of a hot corino towards the prototypical Class I protostar L1551 IRS5, obtained within the ALMA (Atacama Large Millimeter/submillimeter Array) Large Program FAUST (Fifty AU STudy of the chemistry in the disc/envelope system of solar-like protostars). We detected several lines from methanol and its isotopologues (13CH3OH and CH2DOH), methyl formate, and ethanol. Lines are bright towards the north component of the IRS5 binary system, and a possible second hot corino may be associated with the south component. The methanol lines' non-LTE analysis constrains the gas temperature (∼100 K), density (≥1.5 × 108 cm−3), and emitting size (∼10 au in radius). All CH3OH and 13CH3OH lines are optically thick, preventing a reliable measure of the deuteration. The methyl formate and ethanol relative abundances are compatible with those measured in Class 0 hot corinos. Thus, based on this work, little chemical evolution from Class 0 to I hot corinos occurs.
Acceso Abierto
Gas phase Elemental abundances in Molecular cloudS (GEMS) II. On the quest for the sulphur reservoir in molecular clouds: the H2S case
(EDP Sciences, 2020-05-12) Navarro Almaida, D.; Le Gal, R.; Fuente, A.; Rivière Marichalar, P.; Wakelam, V.; Cazaux, S.; Caselli, P.; Laas, J. C.; Alonso Albi, T.; Loison, J. C.; Gerin, M.; Kramer, C.; Roueff, E.; Bachiller, R.; Commercon, B.; Friesen, R.; García Burillo, S.; Goicoechea, J. R.; Giuliano, B. M.; Jiménez Serra, I.; Kirk, J. M.; Lattanzi, V.; Malinen, J.; Marcelino, N.; Martín Doménech, R.; Muñoz Caro, G. M.; Pineda, Jaime E.; Tercero, B.; Treviño Morales, S. P.; Roncero, O.; Tafalla, M.; Ward Thompson, D.; European Research Council (ERC); European Commission (EC); Agencia Estatal de Investigación (AEI); Navarro Almaida, D. [0000-0002-8499-7447]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. Sulphur is one of the most abundant elements in the Universe. Surprisingly, sulphuretted molecules are not as abundant as expected in the interstellar medium and the identity of the main sulphur reservoir is still an open question. Aims. Our goal is to investigate the H2S chemistry in dark clouds, as this stable molecule is a potential sulphur reservoir. Methods. Using millimeter observations of CS, SO, H2S, and their isotopologues, we determine the physical conditions and H2S abundances along the cores TMC 1-C, TMC 1-CP, and Barnard 1b. The gas-grain model NAUTILUS is used to model the sulphur chemistry and explore the impact of photo-desorption and chemical desorption on the H2S abundance. Results. Our modeling shows that chemical desorption is the main source of gas-phase H2S in dark cores. The measured H2S abundance can only be fitted if we assume that the chemical desorption rate decreases by more than a factor of 10 when nH > 2 × 104. This change in the desorption rate is consistent with the formation of thick H2O and CO ice mantles on grain surfaces. The observed SO and H2S abundances are in good agreement with our predictions adopting an undepleted value of the sulphur abundance. However, the CS abundance is overestimated by a factor of 5-10. Along the three cores, atomic S is predicted to be the main sulphur reservoir. Conclusions. The gaseous H2S abundance is well reproduced, assuming undepleted sulphur abundance and chemical desorption as the main source of H2S. The behavior of the observed H2S abundance suggests a changing desorption efficiency, which would probe the snowline in these cold cores. Our model, however, highly overestimates the observed gas-phase CS abundance. Given the uncertainty in the sulphur chemistry, we can only conclude that our data are consistent with a cosmic elemental S abundance with an uncertainty of a factor of 10.
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, Jaime E.; 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.