Examinando por Autor "Sakai, N."

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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, J.; 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
FAUST. II. Discovery of a Secondary Outflow in IRAS 15398−3359: Variability in Outflow Direction during the Earliest Stage of Star Formation?
(The Institute of Physics (IOP), 2021-03-22) Okoda, Y.; Oya, Y.; Francis, L.; Johnstone, D.; Inutsuka, S. I.; Ceccarelli, C.; Codella, C.; Chandler, C. J.; Sakai, N.; Aikawa, Y.; Alves, F.; Balucani, N.; Bianchi, E.; 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.; Hama, T.; Hanawa, T.; Herbst, E.; Hirota, T.; Imai, M.; Isella, A.; Jiménez Serra, I.; Kahane, C.; Lefloch, B.; Loinard, L.; López Sepulcre, A.; Maud, L. T.; Maureira, M. J.; Ménard, F.; Mercimek, S.; Miotello, A.; Moellenbrock, G.; Mori, S.; Murillo, Nadia M.; Nakatani, R.; Nomura, H.; Oba, Y.; O´Donoghue, R.; Ohashi, S.; Ospina Zamudio, J.; Pineda, J. E.; Podio, L.; Rimola, A.; Sakai, T.; Segura Cox, D.; Shirley, Y.; Svoboda, B.; Taquet, V.; Testi, L.; Vastel, C.; Viti, S.; Watanabe, N.; Watanabe, Y.; Witzel, A.; Xue, C.; Zhang, Y.; Zhao, B.; Yamamoto, S.; European Research Council (ERC); Agencia Estatal de Investigación (AEI); Japan Society for the Promotion of Science (JSPS); Okoda, Y. [0000-0003-3655-5270]; Oya, Y. [0000-0002-0197-8751]; Francis, L. [0000-0001-8822-6327]; Johnstone, D. [0000-0002-6773-459X]; Inutsuka, S. I. [0000-0003-4366-6518]; Ceccarelli, C. [0000-0001-9664-6292]; Codella, C. [0000-0003-1514-3074]; Chandler, C. [0000-0002-7570-5596]; Sakai, N. [0000-0002-3297-4497]; Aikawa, Y. [0000-0003-3283-6884]; Alves, F. [0000-0002-7945-064X]; Balucani, N. [0000-0001-5121-5683]; Bianchi, E. [0000-0001-9249-7082]; Bouvier, M. [0000-0003-0167-0746]; Caselli, P. [0000-0003-1481-7911]; De Simone, M. [0000-0001-5659-0140]; Feng, S. [0000-0002-4707-8409]; Fontani, F. [0000-0003-0348-3418]; Hama, T. [0000-0002-4991-4044]; Hanawa, T. [0000-0002-7538-581X]; Herbst, E. [0000-0002-4649-2536]; Hirota, T. [0000-0003-1659-095X]; Imai, M. [0000-0002-5342-6262]; Isella, A. [0000-0001-8061-2207]; Jiménez Serra, I. [0000-0003-4493-8714]; Kahane, C. [0000-0003-1691-4686]; Loinard, L. [0000-0002-5635-3345]; López Sepulcre, A. [0000-0002-6729-3640]; Maud, L. T. [0000-0002-7675-3565]; Maureira, M. J. [0000-0002-7026-8163]; Menard, F. [0000-0002-1637-7393]; Miotello, A. [0000-0002-7997-2528]; Moellenbrock, G. [0000-0002-3296-8134]; Oba, Y. [0000-0002-6852-3604]; Ohashi, S. [0000-0002-9661-7958]; Pineda, J. E. [0000-0002-3972-1978]; Rimola, A. [0000-0002-9637-4554]; Sakai, T. [0000-0003-4521-7492]; Segura Cox, D. [0000-0003-3172-6763]; Svoboda, B. [0000-0002-8502-6431]; Taquet, V. [0000-0003-0407-7489]
We have observed the very low-mass Class 0 protostar IRAS 15398−3359 at scales ranging from 50 to 1800 au, as part of the Atacama Large Millimeter/Submillimeter Array Large Program FAUST. We uncover a linear feature, visible in H2CO, SO, and C18O line emission, which extends from the source in a direction almost perpendicular to the known active outflow. Molecular line emission from H2CO, SO, SiO, and CH3OH further reveals an arc-like structure connected to the outer end of the linear feature and separated from the protostar, IRAS 15398−3359, by 1200 au. The arc-like structure is blueshifted with respect to the systemic velocity. A velocity gradient of 1.2 km s−1 over 1200 au along the linear feature seen in the H2CO emission connects the protostar and the arc-like structure kinematically. SO, SiO, and CH3OH are known to trace shocks, and we interpret the arc-like structure as a relic shock region produced by an outflow previously launched by IRAS 15398−3359. The velocity gradient along the linear structure can be explained as relic outflow motion. The origins of the newly observed arc-like structure and extended linear feature are discussed in relation to turbulent motions within the protostellar core and episodic accretion events during the earliest stage of protostellar evolution.
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.