On the accretion geometry of Cyg X-1 in the low/hard state     

F. Eugenio Barrio  Chris Done  Sergei Nayakshin 《Monthly notices of the Royal Astronomical Society》2003,342(2):557-563

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On the expansions of intermediate orbit for general planetary theory     

Sergei A. Klioner 《Celestial Mechanics and Dynamical Astronomy》1996,66(4):345-363

Intermediate orbit for general planetary theory is constructed in the form of multivariate Fourier series with numerical coefficients. The structure and efficiency of the derived series are illustrated by giving various statistical properties of the coefficients.The ability of the recently proposed elliptic function approach to compress the Fourier series representing the intermediate orbit is investigated. Our results confirm that when mutual perturbations of a pair of planets are considered the elliptic function approach is quite efficient and allows one to compress the series substantially. However, when perturbations of three or more planets are under study the elliptic function approach does not give any advantages.  相似文献   

The problem of clock synchronization: A relativistic approach   总被引：2，自引：0，他引：2  

Sergei A Klioner 《Celestial Mechanics and Dynamical Astronomy》1992,53(1):81-109

The problem of synchronization of the Earth-based clocks has been discussed in the framework of General Relativity Theory. The synchronization is considered as the transformation of the observers' proper time scales to the coordinate time scale of local inertial geocentric reference system, which is single for all the observers. The formulas for the relativistic corrections occurring in some methods of Earth-based clock synchronization (transported clock, duplex communication via geostationary satellite and meteor-burst link, LASSO experiments) have been derived enabling one to attain the accuracy of 0.1 ns.  相似文献   

The Siberian Solar Radio Telescope: the current state of the instrument,observations, and data   总被引：2，自引：0，他引：2  

Grechnev  V.V.  Lesovoi  S.V.  Smolkov  G. Ya.  Krissinel  B.B.  Zandanov  V.G.  Altyntsev  A.T.  Kardapolova  N.N.  Sergeev  R.Y.  Uralov  A.M.  Maksimov  V.P.  Lubyshev  B.I. 《Solar physics》2003,216(1-2):239-272

The Siberian Solar Radio Telescope (SSRT) is one of the world's largest solar radio heliographs. It commenced operation in 1983, and since then has undergone several upgrades. The operating frequency of the SSRT is 5.7 GHz. Since 1992 the instrument has had the capability to make one-dimensional scans with a high time resolution of 56 ms and an angular resolution of 15 arc sec. Making one of these scans now takes 14 ms. In 1996 the capability was added to make full, two-dimensional images of the solar disk. The SSRT is now capable of obtaining images with an angular resolution of 21 arc sec every 2 min. In this paper we describe the main features and operation of the instrument, particularly emphasizing issues pertaining to the imaging process and factors limiting data quality. Some of the data processing and analysis techniques are discussed. We present examples of full-disk solar images of the quiet Sun, recorded near solar activity minimum, and images of specific structures: plages, coronal bright points, filaments and prominences, and coronal holes. We also present some observations of dynamic phenomena, such as eruptive prominences and solar flares, which illustrate the high-time-resolution observations that can be done with this instrument. We compare SSRT observations at 5.7 GHz, including computed `light curves', both morphologically and quantatively, with observations made in other spectral domains, such as 17 GHz radio images, Hα filtergrams and magnetograms, extreme-ultraviolet and X-ray observations, and dynamic radio spectra.  相似文献   

Gravitational cooling and density profile near caustics in collisionless dark matter haloes     

Roya Mohayaee  Sergei F. Shandarin 《Monthly notices of the Royal Astronomical Society》2006,366(4):1217-1229

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Measuring shapes of galaxy images – I. Ellipticity and orientation     

Nurur Rahman  Sergei F. Shandarin 《Monthly notices of the Royal Astronomical Society》2003,343(3):933-948

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Feature modeling approach to simulating Loop Current Frontal Eddies     

Sergei A. Frolov  Lewis M. Rothstein 《Estuarine, Coastal and Shelf Science》2006,70(4):533

Loop Current Frontal Eddies (LCFE) in the Gulf of Mexico are simulated with a regional configuration of the Princeton Ocean Model using a feature-oriented initialization technique. The initialization procedure is based on a prior investigation of stability characteristics of the Loop Current (LC). Zonal channel experiments conducted with a multi-layer intermediate equations model allowed to identify conditions necessary for formation and growth of frontal eddies. The simulations were able to reproduce key features of LCFE-topography interaction in the DeSoto Canyon region observed during the “Eddy Intrusion” study.  相似文献   

The Seyfert 1 galaxy Ark 120. Spectral variability in 1992–2005     

V. T. Doroshenko  S. G. Sergeev  V. I. Pronik 《Astronomy Reports》2008,52(6):442-462

We have studied the variability of the Hβ line and the adjacent continuum in the spectrum of the Seyfert galaxy Ark 120, based on spectral observations of the galaxy’s nucleus obtained in the Crimea in 1992–2005, supplemented by published data for 1988–1996. Irregular variability on various timescales (years to days) can be accompanied by periodic brightness variations in both the continuum and the Hβ line, with a period of P ～ 430 days and an amplitude of Δm ～ 0.2 ^m in the continuum, which were traced for more than 13 cycles. In total, in 1988–2005, the flux variations in the line lag those in the continuum by 55 ± 9 days if calculated from the peak of the cross correlation function, or by 72 ± 7 days, if calculated from the centroid of the CCF. The delay is correlated with the continuum brightness, increasing when the continuum flux increases. The Hβ line profiles indicate both a high degree of diversity and the presence of features that recur after various extended time intervals. Analysis of the evolution of the differences between each individual normalized line profile and the mean normalized profile indicates systematic motion of excesses relative to the average profile from negative to positive radial velocities. In contrast, parts of the Hβ line with low radiation relative to the mean normalized profile evolve in the opposite direction (from the red to the blue Hβ wing). This pattern is also typical for the rotating broad-line region, if this region has the form of a disk. The rotation period exceeds 9000–10000 days, or 25–27 years. The size of the broad-line region calculated form this period corresponds to a reverberation time of no fewer than 30 days, consistent with the results of cross-correlation analysis.  相似文献   

A new approximate solution of parallel whistler-mode dispersion equation     

Sergei S. Sazhin 《Astrophysics and Space Science》1990,172(2):235-247

A new approximation of the real part of the nonrelativistic plasma dispersion function ?Z of a real argument ξ₀ is proposed: namely, $$\Re Z_A (\xi _0 ) = \frac{{2\xi _0 }}{{1 - 2\xi _0^2 }}.$$ This approximation gives the exact value for ?Z when d²?Z/dξ ₀ ² = 0 and gives the correct expressions for the first two terms of its expansion for large ξ₀. On the basis of this approximation, a new approximate expression for whistler-mode refractive index is derived for the case of wave propagation parallel to the magnetic field in a hot anisotropic and dense plasma. Under certain conditions this expression is more convenient for practical applications in magnetospheric and/or astrophysical conditions than other approximate expressions. The approximation ?Z _A was also used in deriving the approximate expression for whistler-mode instability or damping (γ), although in this case it seems to have little merit when compared with the previously used expressions for γ.  相似文献   

New age data on Precambrian volcanic rocks of the khakdon group, eastern Kolyma region     

A. K. Khudoley  V. I. Tkachenko  D. I. Matukov  N. G. Berezhnaya  S. A. Sergeev 《Doklady Earth Sciences》2006,411(2):1357-1361

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