Examinando por Autor "Maud, L. T."

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Acceso Abierto
Chemical complexity in high-mass star formation An observational and modeling case study of the AFGL 2591 VLA 3 hot core
(EDP Sciences, 2019-11-08) Gieser, C.; Semenov, D.; Beuther, H.; Ahmadi, A.; Mottram, J. C.; Henning, T.; Beltrán, M. T.; Maud, L. T.; Bosco, F.; Leurini, S.; Peters, T.; Klaassen, P. D.; Kuiper, R.; Feng, S.; Urquhart, J. S.; Moscadelli, L.; Csengeri, T.; Lumsden, S.; Winters, J. M.; Suri, S.; Zhang, Q.; Pudritz, R.; Palau, A.; Menten, K. M.; Galván Madrid, R.; Wyrowski, F.; Schilke, P.; Sánchez Monge, A.; Linz, H.; Johnston, K. G.; Jiménez Serra, I.; Longmore, S.; Möller, T.; Deutsche Forschungsgemeinschaft (DFG); Agencia Estatal de Investigación (AEI); Ministerio de Economía y Competitividad (MINECO); European Research Council (ERC); Kuiper, R. [0000-0003-2309-8963]; Sánchez Monge, A. [0000-0002-3078-9482]; Galván Madrid, R. [0000-0003-1480-4643]; Leurini, S. [0000-0003-1014-3390]; Ahmadi, A. [0000-0003-4037-5248]; Semenov, D. [0000-0002-3913-7114]; Gieser, C. [0000-0002-8120-1765]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Aims. In order to understand the observed molecular diversity in high-mass star-forming regions, we have to determine the underlying physical and chemical structure of those regions at high angular resolution and over a range of evolutionary stages. Methods. We present a detailed observational and modeling study of the hot core VLA 3 in the high-mass star-forming region AFGL 2591, which is a target region of the NOrthern Extended Millimeter Array (NOEMA) large program CORE. Using NOEMA observations at 1.37 mm with an angular resolution of ~0″. 42 (1400 au at 3.33 kpc), we derived the physical and chemical structure of the source. We modeled the observed molecular abundances with the chemical evolution code MUSCLE (MUlti Stage ChemicaL codE). Results. With the kinetic temperature tracers CH3CN and H2CO we observe a temperature distribution with a power-law index of q = 0.41 ± 0.08. Using the visibilities of the continuum emission we derive a density structure with a power-law index of p = 1.7 ± 0.1. The hot core spectra reveal high molecular abundances and a rich diversity in complex molecules. The majority of the molecules have an asymmetric spatial distribution around the forming protostar(s), which indicates a complex physical structure on scales <1400 au. Using MUSCLE, we are able to explain the observed molecular abundance of 10 out of 14 modeled species at an estimated hot core chemical age of ~21 100 yr. In contrast to the observational analysis, our chemical modeling predicts a lower density power-law index of p < 1.4. Reasons for this discrepancy are discussed. Conclusions. Combining high spatial resolution observations with detailed chemical modeling allows us to derive a concise picture of the physical and chemical structure of the famous AFGL 2591 hot core. The next steps are to conduct a similar analysis for the whole CORE sample, and then use this analysis to constrain the chemical diversity in high-mass star formation to a much greater depth.
Restringido
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
Fragmentation in the massive G31.41+0.31 protocluster
(EDP Sciences, 2021-04-20) Beltrán, M. T.; Rivilla, V. M.; Cesaroni, R.; Maud, L. T.; Galli, D.; Moscadelli, L.; Lorenzani, A.; Ahmadi, A.; Beuther, H.; Csengeri, T.; Etoka, S.; Goddi, C.; Klaassen, P. D.; Kuiper, R.; Kumar, M. S. N.; Peters, T.; Sánchez Monge, Á.; Schilke, P.; Van der Tak, F.; Vig, S.; Zinnecker, H.; Comunidad de Madrid; Deutsche Forschungsgemeinschaft (DFG); European Research Council (ERC); Fundacao para a Ciencia e a Tecnologia (FCT)
Context. ALMA observations at 1.4 mm and ~0.′′2 (~750 au) angular resolution of the Main core in the high-mass star-forming region G31.41+0.31 have revealed a puzzling scenario. On the one hand, the continuum emission looks very homogeneous and the core appears to undergo solid-body rotation, suggesting a monolithic core stabilized by the magnetic field; on the other hand, rotation and infall speed up toward the core center, where two massive embedded free-free continuum sources have been detected, pointing to an unstable core having undergone fragmentation. Aims. To establish whether the Main core is indeed monolithic or if its homogeneous appearance is due to a combination of large dust opacity and low angular resolution, we carried out millimeter observations at higher angular resolution and different wavelengths. Methods. We carried out ALMA observations at 1.4 mm and 3.5 mm that achieved angular resolutions of ~0.′′1 (~375 au) and ~0.′′075 (~280 au), respectively. VLA observations at 7 mm and 1.3 cm at even higher angular resolution, ~0.′′05 (~190 au) and ~0.′′07 (~260 au), respectively, were also carried out to better study the nature of the free-free continuum sources detected in the core. Results. The millimeter continuum emission of the Main core has been clearly resolved into at least four sources, A, B, C, and D, within 1″, indicating that the core is not monolithic. The deconvolved radii of the dust emission of the sources, estimated at 3.5 mm, are ~400–500 au; their masses range from ~15 to ~26 M⊙; and their number densities are several 109 cm−3. Sources A and B, located closer to the center of the core and separated by ~750 au, are clearly associated with two free-free continuum sources, likely thermal radio jets, and are brightest in the core. The spectral energy distribution of these two sources and their masses and sizes are similar and suggest a common origin. Source C has not been detected at centimeter wavelengths, while source D has been clearly detected at 1.3 cm. Source D is likely the driving source of an E–W SiO outflow previously detected in the region, which suggests that the free-free emission might be coming from a radio jet. Conclusions. The observations have confirmed that the Main core in G31 is collapsing, that it has undergone fragmentation, and that its homogeneous appearance previously observed at short wavelengths is a consequence of both high dust opacity and insufficient angular resolution. The low level of fragmentation together with the fact that the core is moderately magnetically supercritical, suggests that G31 could have undergone a phase of magnetically regulated evolution characterized by a reduced fragmentation efficiency, eventually leading to the formation of a small number of relatively massive dense cores.