233 research outputs found
A weak-lensing analysis of the Abell 2163 cluster
No full textAims. We attempt to measure the main physical properties (mass, velocity dispersion, and total luminosity) of the cluster Abell 2163.
Methods. A weak-lensing analysis is applied to a deep, one-square-degree, r-band CFHT-Megacam image of the Abell 2163 field. The observed shear is fitted with Single Isothermal Sphere and Navarro-Frenk-White models to obtain the velocity dispersion and the mass, respectively; in addition, aperture densitometry is used to provide a mass estimate at different distances from the cluster centre. The luminosity function is derived, which enables us to estimate the mass/luminosity ratio.
Results. Weak-lensing analyses of this cluster, on smaller scales, have produced results that conflict with each other. The mass and velocity dispersion obtained in the present paper are compared and found to agree well with values computed by other authors from X-ray and spectroscopic data
A Herschel view of IC 1396 A : unveiling the different sequences of star formation
No full textA.S.A. acknowledges support from the Spanish MICINN/MINECO “Ramón y Cajal” program, grant number RYC-2010-06164, and the action “Proyectos de Investigación fundamental no orientada”, grant number AYA2012-35008. C.E. is partly supported by Spanish MICINN/MINECO grant AYA2011-26202. V.R. is supported by the DLR grant number 50 OR 1109 and by the Bayerischen Gleichstellungsförderung (BGF).Context. The IC 1396 A globule, located to the west of the young cluster Tr 37, is known to host many very young stars and protostars, and is also assumed to be a site of triggered star formation. Aims. Our aim is to test the triggering mechanisms and sequences leading to star formation in Tr 37 and similar regions. Methods. We mapped IC 1396 A with HerscheI/PACS at 70 and 160 μm. The maps reveal the structure of the most embedded parts of the star-forming site in great detail. Results. The HerscheI/PACS maps trace the very embedded protostellar objects and the structure of the cloud. PACS data reveal a previously unknown Class 0 object, labeled IC 1396 A-PACS-1, located behind the ionization front. IC 1396 A-PACS-1 is not detectable with Spitzer, but shows marginal X-ray emission. The data also allow the study of three of the Class I intermediate-mass objects within the cloud. We derived approximate cloud temperatures to study the effect and potential interactions between the protostars and the cloud. The Class 0 object is associated with the densest and coldest part of IC 1396 A. Heating in the cloud is dominated by the winds and radiation of the 06.5 star HD 206267 and, to a lesser extent, by the effects of the Herbig Ac star V 390 Cep. The surroundings of the Class I and Class II objects embedded in the cloud also appear warmer than the sourceless areas, although most of the low-mass objects cannot be individually extracted owing to distance and beam dilution. Conclusions. The observations suggest that at least two episodes of star formation have occurred in IC 1396 A. One would have been the origin of the known, similar to ~1 Myr-old Class I and II objects in the cloud, and a new wave of star formation would have produced the Class 0 source at the tip of the bright-rimmed cloud. From its location and properties, IC 1396 A-PACS-1 is consistent with having been triggered via radiative driven implosion (RDI) induced by HD 206267. The mechanisms behind the formation of the more evolved population of Class objects in the cloud are uncertain. Heating of most of the remaining cloud by Class I/Class II objects and by HD 206267 itself may preclude further star formation in the region.Peer reviewe
The Herschel/PACS view of the Cep OB2 region : global protoplanetary disk evolution and clumpy star formation
No full textA.S.A. acknowledges support by the Spanish MICINN/MINECO “Ramón y Cajal” program, grant number RYC-2010-06164. A.S.A. and M.F. acknowledge support by the action “Proyectos de Investigación fundamental no orientada”, grant number AYA2012-35008. C.E. is partly supported by Spanish MICINN/MINECO grant AYA2011-26202. V.R. is supported by the DLR grant number 50 OR 1109 and by the Bayerischen Gleichstellungsförderung (BGF). T.B. acknowledges support from NASA Origins of Solar Systems grant NNX12AJ04G.Context. The Cep OB2 region, with its two intermediate-aged clusters Tr 37 and NGC7160, is a paradigm of sequential star formation and an ideal site for studies of protoplanetary disk evolution. Aims. We use Herschel data to study the protoplanetary disks and the star formation history of the region. Methods. Herschel/PACS observations at 70 and 160 μm probe the disk properties (mass, dust sizes, structure) and the evolutionary state of a large number of young stars. Far-IR data also trace the remnant cloud material and small-scale cloud structure. Results. We detect 95 protoplanetary disks at 70 μm, 41 at 160 μm, and obtain upper limits for more than 130 objects. The detection fraction at 70 μm depends on the spectral type (88% for K4 or earlier stars, 17% for M3 or later stars) and on the disk type (~50% for full and pre-transitional disks, ~35% for transitional disks, no low-excess/depleted disks detected). Non-accreting disks are not detected, suggesting significantly lower masses. Accreting transition and pre-transition disks have systematically higher 70μm excesses than full disks, suggestive of more massive, flared and/or thicker disks. Herschel data also reveal several mini-clusters in Tr 37, which are small, compact structures containing a few young stars surrounded by nebulosity. Conclusions. Far-IR data are an excellent probe of the evolution of disks that are too faint for sub-millimetre observations. We find a strong link between far-IR emission and accretion, and between the inner and outer disk structure. Herschel confirms the dichotomy between accreting and non-accreting transition disks. Accretion is a powerful measure of global disk evolution: substantial mass depletion and global evolution need to occur to shut down accretion in a protoplanetary disk, even if the disk has inner holes. Disks likely follow different evolutionary paths: low disk masses do not imply opening inner holes, and having inner holes does not require low disk masses. The mini-clusters reveal multi-episodic star formation in Tr 37. The long survival of mini-clusters suggest that they formed from the fragmentation of the same core. Their various morphologies favour different formation/triggering mechanisms acting within the same cluster. The beads-on-a-string structure in one mini-cluster is consistent with gravitational fragmentation or gravitational focusing, acting on very small scales (solar-mass stars in ~0.5 pc filaments). Multi-episodic star formation could also produce evolutionary variations between disks in the same region. Finally, Herschel also unveils what could be the first heavy mass loss episode of the O6.5 star HD206267 in Tr 37.Peer reviewe
Upper Carboniferous and Permian biostratigraphy of the Middle Tianshan
No full textThe biostratigraphic study of the upper Carboniferous and lower Permian stratotype sections
in the Middle Tianshan of Kyrgyzstan enable us to identify foraminifera complexes
that characterize certain intervals of the section, defined as foraminifera zones. In stratigraphic
interval from the Kasimovian to Asselian stage, we distinguish seven foraminifera
zones as follows: 1. Triticites komansuensis — Triticites procerulus, 2. Schwageriniformis arpaensis
— T. turkestanensis, 3. Jigulites corpulentus — Daixina porrecta, 4. Daixina vasilkovskyi
— Quasifusulina kodzhagulica, 5. Daixina (B.) bosbytauensis — Pseudodaixinoides kacagaricus,
6. Occidentoschwagerina alpina, 7. Schwagerina moelleri — Grozdilovia (?) fecunda.
These zones were distinguished based on the study of 350 species of fusulinides, including
65 new endemic species (Djenchuraeva, Getman, 2007, 2010). Occurrence of endemic species
in the zonal complexes hampers the correlation of these zones with coeval strata in
other regions. However, it allows one to reconstruct sharp changes in the facial conditions
of Foraminifera’s existence which resulted from increasing isolation of the eastern part of
the Turkestan ocean. New endemic species are characterized by common features, such as
small initial chamber, close coiling of the helix in the internal rotations and strong folding of
septa in higher forms. Sedimentological observations help to restore depositional environment
of the basin in the eastern part of the Middle Tien Shan. Djenchuraeva A. V. and Gonchar
A. D. (2001) describe shallow litofacies and tempestites in the upper Carboniferous and
Lower Permian sediments of this region. The study of the full composition of foraminifera complexes allows to compare them with the zonal subdivisions of various regions of Central
Asia, Urals, Russian Platform and Donbas
Problems of determination of principle of psychological profile of unknown criminal person in investigational activity
No full textIn the article principle of psychological profile of unknown criminal person in investigational activity is examined. Validity of this approach appears at importance of the use of modelling method as innovative direction of investigation. Thus, an author marks that to application of this method research of theoretical principles and preparation of practical recommendations must be preceded in practical activity of investigator.
The author marks that to the problems of social and psychological description of criminal person, in particular, unknown, in criminalistics and psychological literature certain attention was spared and determines separate scientists (I. М. Luzgin, V. О. Оbrazcov and S. М. Bogomolov, І. S. Safuanov, Yu. V. Chufarovskii and others) works of that were devoted to research of this problem. However, for today, in criminalistics and legal psychology unambigiuous looks are absent in relation to the use of psychological knowledge in investigational activity. Therefore the aim of this article is consideration of separate theoretical problems of the use of modelling method during establishment of unknown criminal person in investigational activity.
By the author of the article of analysis different determinations of «psychological profile of unknown criminal person» were subjected. They are set positive lines and separate positions that in opinion of author are not expedient and important are subjected to criticism. That is why, the author points in conclusions the argued positions in relation to the necessity of the use of psychological profile of unknown criminal person during investigation of criminal realizations in activity of investigator
L’industrie cinématographique allemande après la guerre… froide : année zéro, deuxième prise
No full textCet article tente de faire état de la situation actuelle du cinéma allemand en Allemagne. Pour ce faire, il explore trois filons : la condition périphérique de ce cinéma sur son propre territoire; la conception allemande de l’auteur et de son cinéma; la refonte des conditions de production au lendemain de la réunification de l’Allemagne.This article seeks to account for the cuttent situation of Getman cinema in Germany. Towards this end it explores three veins: the peripherical condition of this cinema on its own territory; the Getman conception of the author and his/het cinema; the remodelling of the conditions of production on the morrow of German reunification
Searching for galaxy clusters in the VST-KIDS survey
No full textWe present the methods and first results of the search for galaxy clusters in the Kilo Degree Survey (KiDS). The adopted algorithm and the criterium for selecting the member galaxies are illustrated. Here we report the preliminary results obtained over a small area (7 deg2), and the comparison of our cluster candidates with those found in the c and SZ Planck catalogues; the analysis to a larger area (148 deg2) is currently in progress. By the KiDS cluster search, we expect to increase the completeness of the clusters catalogue to z = 0.6–0.7 compared to RedMapper
AMICO galaxy clusters in KiDS-DR3: Galaxy population properties and their redshift dependence
No full textA catalogue of galaxy clusters was obtained in an area of 414 up to a redshift z ∼0.8 from the Data Release 3 of the Kilo-Degree Survey (KiDS-DR3), using the Adaptive Matched Identifier of Clustered Objects (amico) algorithm. The catalogue and the calibration of the richness-mass relation were presented in two companion papers. Here, we describe the selection of the cluster central galaxy and the classification of blue and red cluster members, and analyse the main cluster properties, such as the red/blue fraction, cluster mass, brightness, and stellar mass of the central galaxy, and their dependence on redshift and cluster richness. We use the Illustris-TNG simulation, which represents the state-of-the-art cosmological simulation of galaxy formation, as a benchmark for the interpretation of the results. A good agreement with simulations is found at low redshifts (z ≤ 0.4), while at higher redshifts the simulations indicate a lower fraction of blue galaxies than what found in the KiDS-amico catalogue: we argue that this may be due to an underestimate of star-forming galaxies in the simulations. The selection of clusters with a larger magnitude difference between the two brightest central galaxies, which may indicate a more relaxed cluster dynamical status, improves the agreement between the observed and simulated cluster mass and stellar mass of the central galaxy. We also find that at a given cluster mass the stellar mass of blue central galaxies is lower than that of the red ones
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