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31.
Olga L.Ryabukhina Igor I.Zinchenko Manash R.Samal Petr M.Zemlyanukha Dmitry A.Ladeyschikov ANDrej M.Sobolev Christian Henkel Devendra K.Ojha 《天文和天体物理学研究(英文版)》2018,(8)
We present results of a high resolution study of the filamentary infrared dark cloud G192.76+00.10 in the S254-S258 OB complex in several molecular species tracing different physical conditions. These include three isotopologues of carbon monoxide(CO), ammonia(NH3) and carbon monosulfide(CS). The aim of this work is to study the general structure and kinematics of the filamentary cloud, and its fragmentation and physical parameters. The gas temperature is derived from the NH3(J, K) =(1,1),(2, 2) and ~(12)CO(2-1) lines, and the ~(13)CO(1-0), ~(13)CO(2-1) emission is used to investigate the overall gas distribution and kinematics. Several dense clumps are identified from the CS(2-1)data. Values of the gas temperature lie in the range 10-35 K, and column density N(H2) reaches the value 5.1 x 10~(22) cm~(-2). The width of the filament is of order 1 pc. The masses of the dense clumps range from ～ 30 M_☉ to ～ 160 M_☉. They appear to be gravitationally unstable. The molecular emission shows a gas dynamical coherence along the filament. The velocity pattern may indicate longitudinal collapse. 相似文献
32.
Oxygen and nitrogen abundances for a selection of 113607 cold objects from the Sloan Digital Sky Survey (SDSS) spectra are
derived. Values of oxygen abundances 12 + log(O/H) are obtained using three parametric N calibrations, one of which is constructed
in this work. Values of nitrogen abundances 12 + log(N/H) are found with two N calibrations. The values of oxygen abundances
that are derived using three parametric N calibrations are consistent within 0.05 dex for the vast majority of the objects.
It is not improbable that there are systematic differences between the values of oxygen abundances which do not exceed 0.05
dex. The differences between the values of nitrogen abundances which are obtained using ON and NS calibrations reach 0.1 dex. We show that the vast majority of cold SDSS objects are in the same area of the diagram O/H—N/O
as cold H2 regions of nearby galaxies, for which the oxygen and nitrogen abundances are derived through the T
e
-method. This is indirect evidence that the values of oxygen and nitrogen abundances that are found with parametric N calibrations
are reliable. 相似文献
33.
Multidimensional mathematical analysis of a set of abiotic and biotic indices was carried out on the basis of many-year (1958–1984, 1992) observations of the Kuibyshev Reservoir. The character of the space and time dynamics of the samples is studied; the localization of sections of statistically homogeneous data was implemented. Graphs of the long-term spatial taxonomic structure of water masses were analyzed for different periods. The graphs had been formed with the use of the principal component method, neuron network modeling, and self-organizing Kohonen maps. Comprehensive zoning of the reservoir water area was carried out with the help of GIS technologies. 相似文献
34.
I. I. Zinchenko 《Astronomy Letters》2000,26(12):802-805
Based on a CS and C34S survey of dense molecular-cloud cores in regions of high-mass-star formation, we analyze the correlations between line width and size (ΔV-L), as well as between mean density and size (n-L). There is virtually no correlation between ΔV and L (ΔV ∝ L 0.2±0.1). The velocity dispersion is several times higher in absolute value than that in CO and dark clouds of the same size. The mean density decreases with increasing size considerably faster than L ?1, so the column density also decreases. Possible effects of selection and of the technique for determining object parameters on these results are discussed. Possible physical causes of the above correlations are considered. 相似文献
35.
36.
In this paper we develop a statistical approach to resolve the transport problem for the tangential fluctuations of the geomagnetic field in the mantle. For the sake of simplicity we treat the mantle as a thick layer of vacuum and assume in addition that only a radial component of the magnetic field of the core penetrates through the core-mantle boundary. These assumptions allow us to find exact expressions for the tangential field components throughout the mantle. By using such expressions we construct a correlation tensor of tangential components and then, since the mantle is thick enough, study its asymptotic properties on the Earth surface. Incidentally, the correlation tensor trace happens to be equal to the correlation function of the radial component that was obtained by Pilipenko and Sokoloff (1992). Indeed, we provide a simple boundary problem which initially describes the diffusion functions. We also pay a special attention to transformation properties of the correlation tensor and find here some interesting analogies with secular variation data of the geomagnetic field 相似文献