Microvariability of line profiles in the spectrum of the star ι Her     

A. F. Kholtygin  G. A. Galazutdinov  T. E. Burlakova  G. G. Valyavin  S. N. Fabrika  B. -C. Lee 《Astronomy Reports》2006,50(3):220-231

We present the results of a search for and analysis of line-profile variations in the spectrum of the star ι Her. The observations were acquired with the 1.8 m telescope of the Bohyunsan Optical Astronomy Observatory (Republic of Korea) in May–June 2004. We obtained 69 spectra of the star with signal-to-noise ratios ≈300 and a time resolution of 5–7 min. Profile variability was revealed for six lines of HI, HeI, and SiIII, in the central parts of the lines. The variability amplitude is ≈(1–2)% in units of the intensity of the adjacent continuum. Evidence was found for cyclic variations of the lines, with periods from ≈7^h to ≈2.9^d. We conclude that ι Her belongs to the group of slowly pulsating stars.  相似文献   

Influence of Biogenous Elements on Components of the Lake Baikal Plankton Community     

E. A. Silow  D. J. Stom  N. A. Basharova  A. A. Belyaev  N. A. Buntina  O. A. Burlakova  T. A. Dzuban  E. N. Ermakova  N. A. Zausaeva  A. I. Spivak  T. G. Khramtzova  G. V. Shahova  N. G. Sheveleva  N. A. Shestakova 《洁净——土壤、空气、水》1991,19(6):629-634

Fertilization experiments in mesocosms of 1 … 2,000 1 containing up to 0.32 mg/l P and 1.7 mg/l N in summer and in winter did not show any significant changes of the hydrochemical conditions and in the bacterio-plankton. CO₂-assimilation (14-C method) is reduced by circa 10= by nutrient doses, whereas the chlorophyll concentration increases significantly due to addition of P and N at the same time in summer, a decrease taking place in winter. The different courses of development are connected with different reactions of individual species of phytoplankton.  相似文献   

Statistics of magnetic fields for OB stars     

A. F. Kholtygin  S. N. Fabrika  N. A. Drake  V. D. Bychkov  L. V. Bychkova  G. A. Chountonov  T. E. Burlakova  G. G. Valyavin 《Astronomy Letters》2010,36(5):370-379

Based on an analysis of the catalog of magnetic fields, we have investigated the statistical properties of the mean magnetic fields for OB stars. We show that the mean effective magnetic field B of a star can be used as a statistically significant characteristic of its magnetic field. No correlation has been found between the mean magnetic field strength B and projected rotational velocity of OB stars, which is consistent with the hypothesis about a fossil origin of the magnetic field. We have constructed the magnetic field distribution function for B stars, F(B), that has a power-law dependence on B with an exponent of ≈−1.82. We have found a sharp decrease in the function F(B) for B ⩽ 400 G that may be related to rapid dissipation of weak stellar surface magnetic fields.  相似文献   

Line-profile microvariability in OB-star spectra: the Supergiant λ Cep (O6If(n))     

A. F. Kholtygin  N. P. Sudnik  T. E. Burlakova  G. G. Valyavin 《Astronomy Reports》2011,55(12):1105-1114

We observed the bright O6If(n) supergiant λ Cep in 1997 with the 6-m optical telescope of the Special Astrophysical Observatory and in 2007 with the 1.8-m telescope of the Bohyunsan Optical Astronomy Observatory (South Korea). A total of 90 spectra of the star were acquired, with good time resolution (10 minutes), signal-to-noise ratios 150–300, and spectral resolutions of 45 000–60 000. We detected line-profile variations of H, HeI, and HeII lines. It is suggested that the detected variations are due to non-radial photospheric pulsations and the star’s rotation (rotational profile modulation).  相似文献   

Seasonal and spatial variability of the content of suspended organic substances in the active layer of the Black Sea     

Z. P. Burlakova  L. V. Eremeeva  S. K. Konovalov 《Physical Oceanography》2000,10(5):419-454

On the basis of the generalized data of multiannual observations (1985–1994), we analyze the seasonal variability of the vertical and spatial distributions and composition (C_sos, N_sos, C_sos/cha, and C/N) of suspended organic substances (SOS) in the shelf zone and in the upper active layer of the abyssal part of the Black Sea. The results of our analysis enable us to conclude that only a narrow coastal band of the shelf in the northwest and west parts of the sea suffers to an extremely pronounced anthropogenic impact, which manifests itself in a significant increase in the mass of suspended organic substances. The formation of new organic substances and, hence, the mass of suspended organic substances in these regions attain the level of eutrophic waters in the late-spring and summer periods. In the open-sea region, the anthropogenic impact is less pronounced and the spatial distribution of suspended organic substances is determined by the general dynamics of waters and the intensity of phytoplankton production. Translated by Peter V. Malyshev and Dmitry V. Malyshev  相似文献   

Mathematical simulation of the bio-optical state of water in application to the passive probing problem     

V. E. Shemshura  Z. Z. Finenko  Z. P. Burlakova  L. V. Eremeeva 《Physical Oceanography》1995,6(6):421-434

The method of bio-optical modelling of seawater is discussed in application to the passive remote sensing of an ocean within the optical wavelength range. The model implies the presence of two hydrobiological characteristics in the algorithm for the spectral composition of upward radiation, namely the phytoplankton pigment concentration and the total particulate organic matter. The method has been thoroughly tested. The data provided byin situ measurements in the areas accommodating waters of different types (from Case 1 and Case 2) and the modelling results, with the errors being considered, are in good agreement.Translated by Vladimir A. Puchkin.  相似文献   

Estimation of phytoplankton pigments,total suspended matter and the concentration of its components by Secchi depth in Guinea's coastal zone     

Z. P. Burlakova  L. V. Eremeeva  V. E. Shemshura 《Physical Oceanography》1994,5(5):383-393

Relationships between the surface concentrations of phytoplankton pigments (C _ph), total suspended matter (C _sm), particulate organic carbon (C _poc), and total suspended phosphorus (C _sp), on the one hand, and the relative water transparency determined through the Secchi disc depth (z _d), on the other, are analysed using the data compiled in the Guinean coastal waters (Tabunsu and Tonkima river estuaries) during November–December 1990. The functions ofC _ph,C _sm=f(z _d) are matched up with the experimentally derived data, as well as with the model bio-optical state of seawater. The general regression equation has been calculated using the data characteristic of various types of water.Translated by Vladimir A. Puchkin.  相似文献   

Budget and Fluxes of Particulate Organic Carbon and Nitrogen According to the Data on Their Vertical Distribution in the Deep Part of the Black Sea     

Burlakova  Z. P.  Eremeeva  L. V.  Konovalov  S. K. 《Physical Oceanography》2003,13(3):157-170

On the basis of the analysis of the many-year data on the vertical distributions of particulate organic carbon and nitrogen, we compute their annual average amounts for three typical layers of water in the deep part of the Black Sea: for a layer located above the oxycline and characterized by the formation of new portions of particulate organic matter in the course of photosynthesis, inside the oxycline, where the major part of oxygen is consumed and the major part of the flux of particulate organic matter is oxidized, and for the upper part of the anoxic zone characterized by the most active microbiological processes of oxidation of the organic substances and production of sulfides. The available literature data on sedimentation traps are used to study the downward annual average fluxes of particulate organic matter from the euphotic zone into the oxycline and into the anaerobic zone. The seasonal variability of the amounts and fluxes of particulate carbon and nitrogen is revealed.  相似文献   

Magnetic field evolution in OBA stars     

A.?F.?KholtyginEmail author  S.?N.?Fabrika  N.?A.?Drake  V.?D.?Bychkov  L.?V.?Bychkova  G.?A.?Chountonov  T.?E.?Burlakova  G.?G.?Valyavin 《Kinematics and Physics of Celestial Bodies》2010,26(4):181-191

The applications of the spectral analysis methods discovered by Kirchhoff for the investigation of stellar magnetic fields are considered. The statistical properties of the mean magnetic fields for OBA stars have been investigated by analyzing data from two catalogs of magnetic fields. It is shown that the mean effective magnetic field ℬ of a star can be used as a statistically significant characteristic of its magnetic field. The magnetic field distribution functions F(ℬ) have been constructed for B-type and chemically peculiar (CP) stars, which exhibit a power-law dependence on ℬ. A sharp decrease in F(ℬ) in the range of weak magnetic fields has been found. The statistical properties of the magnetic fluxes for main-sequence stars, white dwarfs, and neutron stars are analyzed.  相似文献   

High-resolution fiber-fed echelle spectrograph for the 6-m telescope. I. Optical scheme,arrangement, and control system     

G. G. Valyavin  V. D. Bychkov  M. V. Yushkin  G. A. Galazutdinov  S. V. Drabek  V. S. Shergin  A. N. Sarkisyan  E. A. Semenko  T. E. Burlakova  V. M. Kravchenko  D. O. Kudryavtsev  A. M. Pritychenko  P. G. Kryukov  S. L. Semjonov  F. A. Musaev  S. N. Fabrika 《Astrophysical Bulletin》2014,69(2):224-239

We propose a project of a high-resolution (R = 100 000) fiber-fed spectrograph for comprehensive studies of stellar atmospheres, exoplanet searches, asteroseismological studies, studies of stellar magnetism, active nuclei of bright galaxies, interstellar medium, etc. We present the optical scheme of the instrument. The operating wavelength region spans from 4000 to 7500 Å. We also present the optical scheme of the pre-fiber optic unit of the spectrograph. The unit supports four main modes of spectroscopic observations: the mode of traditional spectroscopy with the spectrum of the studied object taken along with the background spectrum in the immediate vicinity of the object; the mode of the simultaneous recording of the spectrum of the object and that of the wavelength standard; the mode of high-precision spectroscopy with an iodine cell, and the mode of spectropolarimetric observations with the measurement of all the Stokes parameters.  相似文献