Magnetic stars with wide depressions in the continuum. 2. The silicon star with a complex field structure HD 27404     

E. A. Semenko  I. I. Romanyuk  E. S. Semenova  A. V. Moiseeva  D. O. Kudryavtsev  I. A. Yakunin 《Astrophysical Bulletin》2017,72(4):384-390

Observations of the chemically peculiar star HD 27404 with the 6-m SAO RAS telescope showed a strong magnetic field with the longitudinal field component varying in a complicated way in the range of ?2.5 to 1 kG. Fundamental parameters of the star (T_eff = 11 300 K, log g = 3.9) were estimated analyzing photometric indices in the Geneva and in the Stro¨ mgren–Crawford photometric systems. We detected weak radial velocity variations which can be due to the presence of a close star companion or chemical spots in the photosphere. Rapid estimation of the key chemical element abundance allows us to refer HD 27404 to a SiCr or Si+ chemically peculiar A0–B9 star.  相似文献   

Dynamics of Fast Electrons in an Inhomogeneous Plasma with Plasma Beam Instability     

Kudryavtsev  I. V.  Kaltman  T. I.  Vatagin  P. V.  Charikov  Yu. E. 《Geomagnetism and Aeronomy》2019,59(7):838-842

Geomagnetism and Aeronomy - The results of numerical simulation of the one-dimensional propagation of fast electrons in a plasma with Langmuir turbulence are presented. The resonant interaction of...  相似文献   

Solar Activity from the Mid-Second Millennium B.C. to the First Millennium A.D. Based on Radiocarbon Data     

Dergachev  V. A.  Kudryavtsev  I. V.  Nagovitsyn  Yu. A. 《Geomagnetism and Aeronomy》2019,59(7):846-849

Geomagnetism and Aeronomy - The paper reports the results of reconstruction of the heliospheric modulation potential from radiocarbon data for the time interval from the mid-second millennium B.C....  相似文献   

Influence of the Angular Distribution of Langmuir Waves on the Directivity of Radio Emission at Double Plasma Frequency     

Kudryavtsev  I. V.  Kaltman  T. I. 《Geomagnetism and Aeronomy》2020,60(8):1122-1125

Geomagnetism and Aeronomy - The directivity of transverse electromagnetic waves generated in a plasma at a double plasma frequency during the coalescence of plasma waves is calculated for various...  相似文献   

On calculating the Earth's C21 and S21 gravity coefficients in the IERS terrestrial reference frame     

S. M. Kudryavtsev 《Journal of Geodesy》1999,73(9):448-451

Modern models of the Earth's gravity field are developed in the IERS (International Earth Rotation Service) terrestrial reference frame. In this frame the mean values for gravity coefficients of the second degree and first order, C ₂₁(IERS) and S ₂₁(IERS), by the current IERS Conventions are recommended to be calculated by using the observed polar motion parameters. Here, it is proved that the formulae presently employed by the IERS Conventions to obtain these coefficients are insufficient to ensure their values as given by the same source. The relevant error of the normalized mean values for C ₂₁(IERS) and S ₂₁(IERS) is 3×10⁻¹², far above the adopted cutoff (10⁻¹³) for variations of these coefficients. Such an error in C ₂₁ and S ₂₁ can produce non-modeled perturbations in motion prediction of certain artificial Earth satellites of a magnitude comparable to the accuracy of current tracking measurements. Received: 14 September 1998 / Accepted: 20 May 1999  相似文献   

Experimental research on the evolution of wind waves in inhomogeneous currents     

S. A. Grodsky  V. A. Dulov  V. N. Kudryavtsev  O. V. Shul'gin 《Physical Oceanography》1990,1(6):447-459

The results of an aircraft-ship experiment on the spatial variability of parameters of two-dimensional spectra of wind waves are discussed. The observed fields of wave parameters are compared with equations for wave refraction in the currents.Translated by Mikhail M. Trufanov.  相似文献   

The fifth-order analytical solution of the equations of motion of a satellite in orbit around a non-spherical planet     

Sergey M. Kudryavtsev 《Celestial Mechanics and Dynamical Astronomy》1995,61(3):207-215

A high-precise analytical theory of a satellite in orbit around a non-spherical planet has been developed. The Poisson's small parameter method has been used. All secular and short-periodic perturbations proportional up to and including a product of five arbitrary harmonic coefficients of the planetary potential expansion are calculated. Long-periodic perturbations are derived with the accuracy of up to the fourth-order, inclusive. The influence of the high-order perturbations on the motion of ETALON-1 satellite has been investigated. The results of comparison of the numerical and analytical integration of the equations of its motion over a five year interval are as follows:

–	- the r.m.s. difference between the positions is 1.1 cm;
–	- the r.m.s. difference between the ranges is 0.5 cm.

The theory is intended to be used for processing precise laser range measurements of the Earth geodynamical satellites over long-term intervals.  相似文献   

A Compilation of Geophysical Data from the Lazarev Sea and the Riiser-Larsen Sea, Antarctica     

K. Hinz  S. Neben  Y. B. Gouseva  G. A. Kudryavtsev 《Marine Geophysical Researches》2004,25(3-4):233-245

On the basis of new geophysical data acquired by the Federal Institute of Geosciences and Natural Resources (BGR) and the Polar Marine Geological Research Expedition (PMGRE) as well as existing data new geophysical maps were compiled for the Lazarev Sea and the Riiser-Larsen Sea between 10°W and 25°E. The new results are: – The drastic change in the strike direction of the volcanic Explora Wedge between longitudes 10°W and 5°W is accompanied with a gradual change from one major wedge, i.e. the Explora Wedge, into at least two wedge-shaped volcanic constructions, each manifested by a sequence of seaward-dipping reflectors in the seismic records. – The southern Lazarev Sea is best described as a continental margin affected by multiple rifting episodes accompanied with transient volcanism. – A distinct N80°E striking basement depression separates the volcanic-prone continental margin of the southern Lazarev Sea from oceanic crust upon which the Maud Rise rests. The southern scarp of the narrow depression was presumably aligned with the eastern scarp of the Mozambique Ridge during the Early Cretaceous. – The Astrid Ridge proper occupies the transition from the volcanic-prone continental margin of the Lazarev Sea to old oceanic crust of the Riiser -Larsen Sea, and it rests upon a large volcanic apron which covers the basement of the southwestern Riiser-Larsen Sea. – No evidence was found that prolific volcanism has affected the early opening of the Riiser-Larsen Sea. – The Lazarev Sea is a sediment-starved region.  相似文献   

On transformation of the near-surface atmospheric boundary layer in the ocean temperature front area     

S. A. Grodsky  V. N. Kudryavtsev 《Physical Oceanography》1993,4(4):263-273

A two-dimensional, quasi-analytical model for the formation of the internal atmospheric boundary layer in the ocean temperature front area is described, developed on the basis of integral relations for motion and thermal conductivity equations. The computed data are matched with wind speed observations, as well as with direct and indirect dynamic velocity measurements in the air, obtained across the Gulf Stream frontal zone.Translated by V. Puchkin.  相似文献   

Impact Of Dominant Waves On Sea Drag     

V.K. Makin  V.N. Kudryavtsev 《Boundary-Layer Meteorology》2002,103(1):83-99

The impact of air-flow separation from breaking dominant waves is analyzed.This impact results from the correlation of the pressure drop with theforward slope of breaking waves. The pressure drop is parameterized via thesquare of the reference mean velocity. The slope of breaking waves isrelated to the statistical properties of the wave breaking fronts describedin terms of the average total length of breaking fronts. Assuming that thedominant waves are narrow and that the length of breaking fronts is relatedto the length of the contour of the breaking zone it is shown that theseparation stress supported by dominant waves is proportional to thebreaking probability of dominant waves. The breaking probability of dominantwaves, in turn, is defined by the dominant wave steepness. With thedominant wave steepness increasing, the breaking probability is increasedand so does the separation stress. This mechanism explains wave age (youngerwaves being steeper) and finite depth (the spectrum is steeper in shallowwater) dependence of the sea drag. It is shown that dominant waves support asignificant fraction of total stress (sea drag) for young seas due to theair-flow separation that occurs when they break. A good comparison of themodel results for the sea drag with several data sets is reported.  相似文献