178 research outputs found

    W40 region in the Gould Belt : An embedded cluster and H II region at the junction of filaments

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    We present a multiwavelength study of W40 star-forming region using IR observations in UKIRT JHK bands, Spitzer IRAC bands & Herschel PACS bands; 2.12 micron H2 narrow-band imaging; & radio observations from GMRT (610 & 1280 MHz), in a FoV of ~34'x40'. Spitzer observations along with NIR observations are used to identify 1162 Class II/III & 40 Class I sources in the FoV. The NN stellar surface density analysis shows that majority of these YSOs constitute the embedded cluster centered on the source IRS1A South. Some YSOs, predominantly younger population, are distributed along & trace the filamentary structures at lower stellar surface density. The cluster radius is obtained as 0.44pc - matching well with the extent of radio emission - with a peak density of 650pc^-2. The JHK data is used to map the extinction which is subsequently used to compute the cloud mass. It has resulted in 126 Msun & 71 Msun for the central cluster & the northern IRS5 region, respectively. H2 narrow-band imaging displays significant emission, which prominently resembles fluorescent emission arising at the borders of dense regions. Radio analysis shows this region as having blister morphology, with the radio peak coinciding with a protostellar source. Free-free emission SED analysis is used to obtain physical parameters of the overall region & the IRS5 sub-region. This multiwavelength scenario is suggestive of star formation having resulted from merging of multiple filaments to form a hub. Star formation seems to have taken place in two successive epochs, with the first epoch traced by the central cluster & the high-mass star(s) - followed by a second epoch which is spreading into the filaments as uncovered by the Class I sources & even younger protostellar sources along the filaments. The IRS5 HII region displays indications of swept-up material which has possibly led to the formation of protostars.Comment: 17 pages, 12 figures, 2 tables. Accepted for publication in The Astrophysical Journa

    Multi-frequency Studies of Massive Cores with Complex Spatial and Kinematic Structures

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    Five regions of massive star formation have been observed in various molecular lines in the frequency range 8589\sim 85-89 GHz. The studied regions possess dense cores, which host young stellar objects. The physical parameters of the cores are estimated, including kinetic temperatures (2040\sim 20-40 K), sizes of the emitting regions (0.10.6\sim 0.1-0.6 pc), and virial masses (40500M\sim 40-500 M_{\odot}). Column densities and abundances of various molecules are calculated in the local thermodynamical equilibrium approximation. The core in 99.982+4.17, associated with the weakest IRAS source, is characterized by reduced molecular abundances. Molecular line widths decrease with increasing distance from the core centers (bb). For b\ga 0.1~pc, the dependences ΔV(b)\Delta V(b) are close to power laws (bp\propto b^{-p}), where pp varies from 0.2\sim 0.2 to 0.5\sim 0.5, depending on the object. In four cores, the asymmetries of the optically thick HCN(1--0) and HCO+^+(1--0) lines indicate systematic motions along the line of sight: collapse in two cores and expansion in two others. Approximate estimates of the accretion rates in the collapsing cores indicate that the forming stars have masses exceeding the solar mass.Comment: 18 pages, 7 figures, 6 table

    THE MAIN TASK IS THE IMPROVEMENT OF THE ORGANIZATIONAL AND ECONOMIC MECHANISM FOR THE DEVELOPMENT OF RUSSIAN ENTERPRISES

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    Purpose: the purpose of this article is to justify the choice of the strategic direction of effective development of the national economy of Russia. The authors see the solution of this problem on the way of improving the organizational and economic mechanism of the functioning of Russian enterprises. This problem is considered to be one of the main authors in the consolidation of society and its mobilization for the implementation of the tasks set in the may Decree of the President of the Russian Federation (№ 204 from 2018).Methods: the study was conducted using the methods of systematic, logical, comparative analysis, involving Russian and foreign experience in solving social and economic problems. Particular attention was paid to the validity of the conclusions.Results: national economic problems are touched upon through the prism of the economy of enterprises. An attempt has been made to prove the dependence of the acceleration of the rates of economic development on the improvement of the enterprise's internal economic mechanism. In the postindustrial society, the role of enterprises as the main link in the production of material goods and the provision of services is not diminished, despite the accelerated introduction of scientific and technological progress and the increase in the value of personal property. The improvement of the internal structure of enterprises proposed in the article can significantly reduce the negative consequences of the privatization of state property. According to the authors, this will improve the efficiency of the use of human capital in terms of all its components: ordinary workers, managers, specialists, owners.Conclusions and Relevance: currently, there is a situation in which the owners of enterprises (mainly large ones) have practically unlimited rights and very limited liability for the results of the work of their enterprises. This situation hinders the development of the productive forces of society. The proposed concept of an "effective enterprise" means solidary management of enterprises (ultimately solidary management of the economy). It provides for a system of measures to remedy the situation. The first steps in this direction are the following: 1) the creation of a balanced system of enterprise management; 2) democratization of management and development of the institution of collective (people's) enterprises; 3) the movement in the direction of restraint unrestrained competition and finding ways of cooperation not only within enterprises but also in the relations between all participants of the process of production and realization of products, as well as authorities at all levels; 4) streamlining the processes for the establishment and liquidation of enterprises; 5) the active implementation of multilevel and multidimensional strategic planning. It is not possible to implement these measures in a short time. But the movement along this path creates systemic conditions for accelerating economic growth

    МОДЕРНИЗАЦИЯ, ИННОВАЦИИ, РАЗВИТИЕ (некоторые факторы, тормозящие развитие экономики)

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    .В статье анализируются проблемы, сдерживающие движение России по пути модернизации, инноваций, развития. Автор считает, что неспособность правительства, следующего неолиберальным курсом, добиться успехов в экономике, вынуждает его для объяснения этого положения заниматься мифотворчеством. Автор согласен с профессором Массачусетского университета Л. Грэхэмом, что для России эта проблема в основном социальная и ее решение видится в ускорении формирования гражданского общества и усилении в нем демократических начал

    Simultaneous evidence of edge collapse and hub-filament configurations: A rare case study of a Giant Molecular Filament G45.3+0.1

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    We study multiwavelength and multiscale data to investigate the kinematics of molecular gas associated with the star-forming complexes G045.49+00.04 (G45E) and G045.14+00.14 (G45W) in the Aquila constellation. An analysis of the FUGIN 13^{13}CO(1-0) line data unveils the presence of a giant molecular filament (GMF G45.3+0.1; length \sim75 pc, mass \sim1.1×\times106^{6} M_{\odot}) having a coherent velocity structure at [53, 63] km s1^{-1}. The GMF G45.3+0.1 hosts G45E and G45W complexes at its opposite ends. We find large scale velocity oscillations along GMF G45.3+0.1, which also reveals the linear velocity gradients of -0.064 and ++0.032 km s1^{-1} pc1^{-1} at its edges. The photometric analysis of point-like sources shows the clustering of young stellar object (YSO) candidate sources at the filament's edges where the presence of dense gas and HII regions are also spatially observed. The Herschel continuum maps along with the CHIMPS 13^{13}CO(3-2) line data unravel the presence of parsec scale hub-filament systems (HFSs) in both the sites, G45E and G45W. Our study suggests that the global collapse of GMF G45.3+0.1 is end-dominated, with addition to the signature of global nonisotropic collapse (GNIC) at the edges. Overall, GMF G45.3+0.1 is the first observational sample of filament where the edge collapse and the hub-filament configurations are simultaneously investigated. These observations open up the new possibility of massive star formation, including the formation of HFSs.Comment: 23 pages, 12 figures, 1 table, Accepted for publication in The Astrophysical Journa

    Rigorous Analysis of Singularities and Absence of Analytic Continuation at First Order Phase Transition Points in Lattice Spin Models

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    We report about two new rigorous results on the non-analytic properties of thermodynamic potentials at first order phase transition. The first one is valid for lattice models (d2d\geq 2) with arbitrary finite state space, and finite-range interactions which have two ground states. Under the only assumption that the Peierls Condition is satisfied for the ground states and that the temperature is sufficiently low, we prove that the pressure has no analytic continuation at the first order phase transition point. The second result concerns Ising spins with Kac potentials Jγ(x)=γdϕ(γx)J_\gamma(x)=\gamma^d\phi(\gamma x), where 0<γ<10<\gamma<1 is a small scaling parameter, and ϕ\phi a fixed finite range potential. In this framework, we relate the non-analytic behaviour of the pressure at the transition point to the range of interaction, which equals γ1\gamma^{-1}. Our analysis exhibits a crossover between the non-analytic behaviour of finite range models (γ>0\gamma>0) and analyticity in the mean field limit (γ0\gamma\searrow 0). In general, the basic mechanism responsible for the appearance of a singularity blocking the analytic continuation is that arbitrarily large droplets of the other phase become stable at the transition point.Comment: 4 pages, 2 figure

    Fragmentation and dynamics of dense gas structures in the proximity of massive young stellar object W42-MME

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    We present an analysis of the dense gas structures in the immediate surroundings of the massive young stellar object (MYSO) W42-MME, using the high-resolution (0''.31×\times0''.25) ALMA dust continuum and molecular line data. We performed a dendrogram analysis of H13^{13}CO+^{+} (4-3) line data to study multi-scale structures and their spatio-kinematic properties, and analyzed the fragmentation and dynamics of dense structures down to \sim2000 AU scale. Our results reveal 19 dense gas structures, out of which 12 are leaves and 7 are branches in dendrogram terminology. These structures exhibit transonic-supersonic gas motions (1<M<5<\mathcal{M}<5) with overvirial states (αvir2\alpha_{\rm vir}\geq2). The non-thermal velocity dispersion-size relation (σntL\sigma_{\rm nt}-L) of dendrogram structures shows a weak negative correlation, while the velocity dispersion across the sky (δVlsr\delta\mathit{V_{\rm lsr}}) correlates positively with structure size (LL). Velocity structure function (S2(l)1/2S_{2}(l)^{1/2}) analysis of H13^{13}CO+^{+} data reveals strong power-law dependencies with lag (ll) up to a scale length of \lesssim 6000 AU. The mass-size (MRM-R) relation of dendrogram structures shows a positive correlation with power-law index of 1.73±\pm0.23, and the leaf L17 hosting W42-MME meets the mass-size conditions for massive star formation. Blue asymmetry is observed in the H12^{12}CO+^{+} (4-3) line profiles of most of the leaves, indicating infall. Overall, our results observationally support the hierarchical and chaotic collapse scenario in the proximity of the MYSO W42-MME.Comment: 16 pages, 13 figures, 1 Table, Accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS) Journa

    General Theory of Lee-Yang Zeros in Models with First-Order Phase Transitions

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    We present a general, rigorous theory of Lee-Yang zeros for models with first-order phase transitions that admit convergent contour expansions. We derive formulas for the positions and the density of the zeros. In particular, we show that for models without symmetry, the curves on which the zeros lie are generically not circles, and can have topologically nontrivial features, such as bifurcation. Our results are illustrated in three models in a complex field: the low-temperature Ising and Blume-Capel models, and the qq-state Potts model for qq large enough.Comment: 4 pgs, 2 figs, to appear in Phys. Rev. Let

    Density Profiles in Molecular Cloud Cores Associated with High-Mass Star-Forming Regions

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    Radial density profiles for the sample of dense cores associated with high-mass star-forming regions from southern hemisphere have been derived using the data of observations in continuum at 250 GHz. Radial density profiles for the inner regions of 16 cores (at distances \la 0.2-0.8 pc from the center) are close on average to the ρrα\rho\propto r^{-\alpha} dependence, where α=1.6±0.3\alpha=1.6\pm 0.3. In the outer regions density drops steeper. An analysis with various hydrostatic models showed that the modified Bonnor-Ebert model, which describes turbulent sphere confined by external pressure, is preferable compared with the logotrope and polytrope models practically in all cases. With a help of the Bonnor-Ebert model, estimates of central density in a core, non-thermal velocity dispersion and core size are obtained. The comparison of central densities with the densities derived earlier from the CS modeling reveals differences in several cases. The reasons of such differences are probably connected with the presence of density inhomogenities on the scales smaller than the telescope beam. In most cases non-thermal velocity dispersions are in agreement with the values obtained from molecular line observations.Comment: 12 pages, 3 figures, 4 table
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