Some regularities in the variation of the Balmer line profiles in the P Cyg spectrum     

Nevena St. Markova 《Astrophysics and Space Science》1986,123(1):5-19

In the Coudé focus of the 2 m RCC telescope at the National Astronomical Observatory of the Bulgarian Academy of Science 47 spectrograms covering the range from 3500 to 4900 Å (about 1400 Å) with a reciprocal dispersion of 9 Å mm^–1 and a spectral resolution of 0.18 Å were obtained. The photometric and position behaviour of Balmer lines were investigated over a long time-scale, i.e. March 1981 to August 1982.The hydrogen line profiles were rectified in the way discribed by de Groot (1969). It is found that the absorption consists of three and sometimes four components. Their position behaviour may be expalined by the existence of two kinds of shells: pulsating and steadily expanding, and it is quite possible that shells of the first type may become shells of the second type in the outer parts of the P Cyg envelope.The total emission and absorption equivalent widths of the H11, H9, and H lines change with conspicuous minima and maxima. The amplitude of these variations increases with decrease in the upper quantum number. For example,W _tot ^abs change by about 38% for H and 22% for H9.Our data suggest a periodic change in the radial velocities, intensity of each separate absorption component, total equivalent widths and profiles.  相似文献   

Morphology and variability of helium line profiles in the P Cygni spectrum     

N. Markova 《Astrophysics and Space Science》1993,201(1):61-70

The morphology and variability of 13 helium lines in the P Cygni optical spectrum have been studied in detail over a period of three years. It is found that most lines in the sample have often shown profiles with a complicated structure: discrete components are superposed on a broader underlying P Cyg profile. Multiple sets of components were frequently observed. The radial velocity of the discrete components varies with time. In this article the velocity evolution of two sets of components is studied in detail and the corresponding velocity laws are derived. It is found that the velocity variations in the helium and hydrogen discrete components are correlated. The recurrence timescale for the appearance of new helium components is estimated.An attempt is made for a qualitative interpretation of the obtained results.  相似文献   

Energy of acoustic signals in a borehole     

I. Markova  G. Ronquillo Jarillo  M. Markov 《Geophysical Prospecting》2019,67(3):508-518

In the present article, the dependencies of the acoustic signal total energy and the energies of the wave packets of different types of the waves on the elastic parameters and permeability of rocks have been studied. We have considered traditional logging tools containing acoustical monopole source. Calculations were performed in a frequency range of dozens of kilohertz, typical for acoustic well logging. It was shown that in a typical high-velocity formation (v_s > v_f, where v_s and v_f are the velocities of the shear wave in the rock and of the compressional wave in the borehole fluid, respectively), the pseudo-Rayleigh waves, whose elastic properties depend mainly on the shear modulus of the rock, contributed significant energy to the total signal energy in the borehole. The energies of different wave packets depend on the permeability in different ways. The greatest sensitivity to permeability change has been shown by the acoustic signal total energy and the energy of the low-velocity part of the pseudo-Rayleigh wave packet. The theoretical analysis was illustrated by real sonic log data.  相似文献   

Propagation of Elastic Compressional Waves in a Porous-Fractured Medium Saturated with Immiscible Fluids     

Markov  M. G.  Markova  I. A.  Jarillo  G. F. Ronquillo  Pervago  E. V. 《Izvestiya Physics of the Solid Earth》2020,56(3):357-363

Izvestiya, Physics of the Solid Earth - The problem of calculating the reflection and transmission coefficients of elastic P-wave incident from a porous half-space onto a fluid-filled crack is...  相似文献   

Geometrical spreading factor of head waves in cased and open boreholes     

I. A. Markova  S. N. Sadovnychiy 《Izvestiya Physics of the Solid Earth》2011,47(9):827-834

Factors (coefficients) of geometrical spreading of compressional and shear head waves are calculated for an impulse multipole source of elastic oscillations in boreholes. It is shown that the length of the logging tool (i.e., the distance between the source and the nearest receiver) used for sonic measurements and the velocities of elastic waves in the medium both contribute to the factor of geometrical spreading. For a high-velocity formation (the shear wave velocity in the rock is higher than the compressional wave velocity in the fluid that fills the borehole) and a sufficiently long sonic tool with a monopole source, the coefficient of geometrical spreading is approximated by asymptotic formula 1/Z [Roever et al., 1974; Krauklis and Krauklis, 1976], where Z is the length of the tool; i.e., the amplitude of the compressional head wave decreases proportionally to the distance between the source and the receiver. In acoustically soft formations, this approximation is inapplicable even for long tools with length Z > 4 m. Waveforms in cased boreholes have a significant frequency dispersion even in case of good-quality cementing, and the factor of geometrical spreading there depends considerably on the length of the tool and the elastic properties of the rocks.  相似文献   

Environments of the Russian Plain during the Middle Valdai Briansk Interstade (33,000–24,000 yr B.P.) Indicated by Fossil Mammals and Plants     

Anastasia K. Markova  Alexandra N. Simakova  Andrei Yu. Puzachenko  Lev M. Kitaev 《Quaternary Research》2002,57(3):391

Abundant mammal (45 localities) and plant (52 sections) fossil data collected from the Russian Plain deposits of the Middle Valdai Briansk Interstade indicate a period of noticeable warming. These materials were jointly analyzed. The data were organized in the database software PARADOX and then moved to the GIS program ARC/INFO. Mathematical methods as well as traditional research methods were used for the analysis. The reconstructed biogeographical provinces illustrate the specific environmental and climatic conditions of the Briansk Interstade. Analogues of modern natural zones did not exist at this time on the Russian Plain. The Briansk landscapes reflect the moderate-cool climate of this period, when the majority of northern subarctic plant and mammal species extended their ranges considerably to the south to the Central Russian Plain. At the same time, steppe species penetrated farther north and west. This combination shows that the continuous forest zone was destroyed during the Briansk Inter-stade. Five biogeographical provinces have been reconstructed from the north to the south for the Russian Plain during the Briansk warming on the basis of joint analysis of mammalian and botanical data.  相似文献   

On the recording of regions with increased plasma density on the Sun     

L. N. Kurochka  I. P. Kryachko  E. Markova 《Solar physics》1992,139(2):275-277

For the purpose of studying the statistics, dynamics, and morphology of parts of the solar surface with enhanced emission measure and considerable inhomogeneities of electron concentration, it is suggested that a new type of solar observation be introduced: taking filtergrams by means of interference filters, calculated for the Balmer continuum limit and the region of the blue continuum. To determine accurately the inhomogeneity of the electron concentration in an object, it is suggested to scan the surface of the object and record the spectrum of the blue continuum by means of a spectrochronograph.  相似文献   

Using multidimensional analysis and information functions for macro description of European natural complexes in the second part of the Late Pleistocene and the Holocene     

A. Yu. Puzachenko  A. K. Markova 《Doklady Earth Sciences》2011,437(1):380-382

This article analyzes the effect of geographic factors on variations in the species diversity of mammals and plants for the European territory. Multidimensional analysis and a number of information parameters have been applied for the first time, which allowed identifying objective indicators of mammal and plant diversity for different time periods in the Late Pleistocene and the Holocene.  相似文献   

Radiocarbon dates of late quaternary mammals in the Archangelsk Region and their contribution to reconstructions of the last glaciation in Eastern Europe     

D. V. Ponomarev  A. K. Markova  T. van Kolfschoten  J. van der Plicht 《Doklady Earth Sciences》2012,444(2):706-710

Twelve new AMS (Accelerator Mass Spectrometry) dates of large Quaternary mammal remains were reported: mammoth (Mammuthus primigenius, bison (Bison priscus), and musk ox (Ovibos pallantis) found in the Archangelsk Region. The absolute age of the identified samples varies from 46 000 to 22 000 calibrated years ago. These data suggest that a substantial part of the Archangelsk Region was not covered by ice during the indicated time interval.  相似文献   

The behaviour of certain helium lines in the P Cygni spectrum     

Nevena Markova 《Astrophysics and Space Science》1989,158(1):89-93

Sixty-two spectrograms of the supergiant P Cyg, obtained with the Coudé spectrograph of the 2 m RCC telescope at NAO (National Astronomical Observatory, Bulgaria) were used in order to study the behaviour (we mean the displacements of the absorption components only) of the Hei spectrum of this star. Twelve lines from four series (2³ P ⁰–n³S, 2³P⁰ –n ³ D, 2 ¹ P ⁰ –n ¹ D, and 2¹ S–n ¹ P ⁰) were examined. It was established that all observed cases can be reduced to a few (three or four) which are typical. These cases are stated in the form of the comparison between the hydrogen and helium lines. All profiles were rectified and their complex structure was taken into consideration. The fixed peculiarities were explained by an optical depth effect.  相似文献