Suchergebnisse

Inscripción en la parte superior: "FRANCIA." ; Inscripción en la parte inferior: "REPUBLICA / 1795"

Inscripción en la parte superior: "FRANCIA." ; Inscripción: "Regimiento de Dromedarios. Espedicion á Egipto." ; Inscripción en la parte inferior: "REPUBLICA / 1798"

Inscripción en la parte superior: "FRANCIA." ; Inscripción en la parte inferior izquierda: "Soldado de Infanteria de Línea." ; nscripción en la parte inferior derecha: "Oficial de Infanteria Ligera" ; Inscripción en la parte inferior: "REPUBLICA / 1795"

Inscripción en la parte superior: "ESPAÑA." ; Inscripción en la parte inferior: "SOLDADOS DE INFANTERÍA GODA. Primeros tiempos de dominacion en la Peninsula"

Inscripción en la parte superior: "ESPAÑA." ; Inscripción en la parte inferior izquierda: "Soldado de infanteria del tiempo de la dominacion Romana. / del 200 antes de J.C. al 469 de la era vulgar." ; Inscripción en la parte inferior derecha: "Soldado de los primitivos Godos. / 469 de la era vulgar." ; Estampa separada de: Album de la infanteria española desde sus primitivos tiempos hasta el dia / por el General Conde de Clonard. -- Madrid : Impr. y Lit. Militar del Atlas S. Bernardino, 1861

Inscripción en la parte superior: "ESPAÑA." ; Inscripción en la parte inferior izquierda: "Fenicio / año 1600 antes de J.C." ; Inscripción en la parte inferior derecha: "Soldado español de infanteria / año 260 antes de la era vulgar." ; Estampa separada de: Album de la infanteria española desde sus primitivos tiempos hasta el dia / por el General Conde de Clonard. -- Madrid : Impr. y Lit. Militar del Atlas S. Bernardino, 1861

Aims. We aim to reveal the physical properties and chemical composition of the cores in the California molecular cloud (CMC), so as to better understand the initial conditions of star formation. Methods. We made a high-resolution column density map (18.2′′) with Herschel data, and extracted a complete sample of the cores in the CMC with the fellwalker algorithm. We performed new single-pointing observations of molecular lines near 90 GHz with the IRAM 30m telescope along the main filament of the CMC. In addition, we also performed a numerical modeling of chemical evolution for the cores under the physical conditions. Results. We extracted 300 cores, of which 33 are protostellar and 267 are starless cores. About 51% (137 of 267) of the starless cores are prestellar cores. Three cores have the potential to evolve into high-mass stars. The prestellar core mass function (CMF) can be well fit by a log-normal form. The high-mass end of the prestellar CMF shows a power-law form with an index α = -0.9 ± 0.1 that is shallower than that of the Galactic field stellar mass function. Combining the mass transformation efficiency (ϵ) from the prestellar core to the star of 15 ± 1% and the core formation efficiency (CFE) of 5.5%, we suggest an overall star formation efficiency of about 1% in the CMC. In the single-pointing observations with the IRAM 30m telescope, we find that 6 cores show blue-skewed profile, while 4 cores show red-skewed profile. [HCO + ]/[HNC] and [HCO + ]/[N 2 H + ] in protostellar cores are higher than those in prestellar cores; this can be used as chemical clocks. The best-fit chemical age of the cores with line observations is ~5 × 10 4 yr. © ESO 2018. ; Chinese Government Scholarship: 201804910583 ; 2017YFA0402600, 2017YFA0402702 ; Russian Science Foundation, RSF: 18-12-00351 ; Deutsche Forschungsgemeinschaft, DFG: WA3628-1/1 ; National Basic Research Program of China (973 Program): 2015CB857101 ; National Natural Science Foundation of China, NSFC: 11763002, U1431111, 11721303, 11703040, 11703074 ; Acknowledgements. We acknowledge valuable comments from the referee. We thank Charles J. Lada for useful discussion on the manuscript. We thank A. Men'shchikov, D. S. Berry, and S. Bardeau for their technical support with Getsources, Starlink and Gildas, respectively. This work is supported by National Key R&D Program of China (No. 2017YFA0402600; 2017YFA0402702), National Key Basic Research Program of China (973 Program) (No. 2015CB857101), National Natural Science foundation of China (No. 11703040; 11703074; 11721303; 11763002; U1431111), and Chinese Government Scholarship (No. 201804910583). D.A.S. acknowledges support from the Heidelberg Institute of Theoretical Studies for the project "Chemical kinetics models and visualization tools: Bridging biology and astronomy". A.I.V. acknowledges support by the Russian Science Foundation (No. 18-12-00351). K.W. acknowledges support by the German Research Foundation (grant WA3628-1/1).

Support for this work was provided by the NASA Solar System Observations program (80NSSC20K0673), the Space Telescope Science Institute (HST-GO-15372), the National Science Foundation (PHY-2010970), the National Research Foundation (NRF; No. 2019R1I1A1A01059609), the MINEDUC-UA project ESR1795, the European Union H2020-MSCA-ITN-2019 under Grant no. 860470 (CHAMELEON), and by the Novo Nordisk Foundation Interdisciplinary Synergy Program (NNF19OC0057374). ; Cometary activity is a manifestation of sublimation-driven processes atthe surface of nuclei. However, cometary outbursts may arise from other processes that are not necessarily driven by volatiles. In order to fully understand nuclear surfaces and their evolution, we must identify the causes of cometary outbursts. In that context, we present a study of mini-outbursts of comet 46P/Wirtanen. Six events are found in our long-term lightcurve of the comet around its perihelion passage in 2018. The apparent strengths range from -0.2 to -1.6 mag in a 5" radius aperture, and correspond to dust masses between ∼104 to 106 kg, but with large uncertainties due to the unknown grain size distributions. However, the nominal mass estimates are the same order of magnitude as the mini-outbursts at comet 9P/Tempel 1 and 67P/Churyumov-Gerasimenko, events which were notably lacking at comet 103P/Hartley 2. We compare the frequency of outbursts at the four comets, and suggest that the surface of 46P has large-scale (∼10-100 m) roughness that is intermediate to that of 67P and 103P, if not similar to the latter. The strength of the outbursts appear to be correlated with time since the last event, but a physical interpretation with respect to solar insolation is lacking. We also examine Hubble Space Telescope images taken about 2 days following a near-perihelion outburst. No evidence for macroscopic ejecta was found in the image, with a limiting radius of about 2 m. ; Publisher PDF ; Peer reviewed