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1.
We show that the set of observational characteristics for low-mass X-ray binaries in the optical and X-ray bands can be explained in terms of the model of an optically thick accretion disk with an atmosphere irradiated by a central X-ray source. We show that this set of observational data can be successfully used to measure the orbital inclination of a binary, the geometric parameters of its accretion disk, and the reprocessing time of X-emission to optical one. For the burster GS 1826-238, a low-mass X-ray binary with a neutron star, we have estimated the binary inclination and the thickness of the disk atmosphere at the outer edge from the mean optical flux and the amplitude of periodic modulations in the optical light curve: i = 62.5° ± 5.5° and H d/R d = 0.145 ± 0.009. The optical response time of the binary to an X-ray burst disagrees with the geometric delay in the propagation of X-ray photons in the binary. We believe that this points to a finite X-ray reprocessing/reradiation time, 1.0 s ≲ τ repr ≲ 2.2 s, in the hot atmosphere above the accretion disk.  相似文献   
2.
Izvestiya, Atmospheric and Oceanic Physics - We study in detail the source parameters, seismotectonic position, and macroseismic effects of the February 3, 2016, earthquake that occurred in the...  相似文献   
3.
The Astronomical Röntgen Telescope X-ray Concentrator (ART-XC) is a hard X-ray telescope with energy response up to 30 keV, to be launched on board the Spectrum Röntgen Gamma (SRG) spacecraft in 2018. ART-XC consists of seven identical co-aligned mirror modules. Each mirror assembly is coupled with a CdTe double-sided strip (DSS) focal-plane detector. Eight X-ray mirror modules (seven flight and one spare units) for ART-XC were developed and fabricated at the Marshall Space Flight Center (MSFC), NASA, USA. We present results of testing procedures performed with an X-ray beam facility at MSFC to calibrate the point spread function (PSF) of the mirror modules. The shape of the PSF was measured with a high-resolution CCD camera installed in the focal plane with defocusing of 7 mm, as required by the ART-XC design. For each module, we performed a parametrization of the PSF at various angular distances Θ. We used a King function to approximate the radial profile of the near on-axis PSF (Θ < 9 arcmin) and an ellipse fitting procedure to describe the morphology of the far off-axis angular response (9 < Θ < 24 arcmin). We found a good agreement between the seven ART-XC flight mirror modules at the level of 10%. The on-axis angular resolution of the ART-XC optics varies between 27 and 33 arcsec (half-power diameter), except for the spare module.  相似文献   
4.
We investigate the relation between the optical (g-band) and X-ray (0.5–10 keV) luminosities of accreting nonmagnetic white dwarfs. According to the present-day counts of the populations of star systems in our Galaxy, these systems have the highest space density among the close binary systems with white dwarfs. We show that the dependence of the optical luminosity of accreting white dwarfs on their X-ray luminosity forms a fairly narrow one-parameter curve. The typical half-width of this curve does not exceed 0.2–0.3 dex in optical and X-ray luminosities, which is essentially consistent with the amplitude of the aperiodic flux variability for these objects. At X-ray luminosities L x ~ 1032 erg s?1 or lower, the optical g-band luminosity of the accretion flow is shown to be related to its X-ray luminosity by a factor ~2–3. At even lower X-ray luminosities (L x ? 1030 erg s?1), the contribution from the photosphere of the white dwarf begins to dominate in the optical spectrum of the binary system and its optical brightness does not drop below M g ~ 13–14. Using the latter fact, we show that in current and planned X-ray sky surveys, the family of accreting nonmagnetic white dwarfs can be completely identified to the distance determined by the sensitivity of an optical sky survey in this region. For the Sloan Digital Sky Survey (SDSS) with a limiting sensitivity m g ~ 22.5, this distance is ~400–600 pc.  相似文献   
5.
We present spectra for 34 accretion-powers X-ray pulsars and one millisecond pulsar that were within the field of view of the INTEGRAL observatory over two years (December 2002–January 2005) of its in-orbit operation and that were detected by its instruments at a statistically significant level (> 8σ in the energy range 18–60 keV). There are seven recently discovered objects of this class among the pulsars studied: 2RXP J130159.6-635806, IGR/AX J16320-4751, IGR J16358-4726, AX J163904-4642, IGR J16465-4507, SAX/IGR J18027-2017, and AX J1841.0-0535. We have also obtained hard X-ray (>20 keV) spectra for the accretion-powered pulsars RX J0146.9+6121, AX J1820.5-1434, and AX J1841.0-0535 for the first time. We analyze the evolution of spectral parameters as a function of the intensity of the sources and compare these with the results of previous studies.  相似文献   
6.
We have computed a spherically symmetric model for the interaction of matter ejected during the outburst of a classical nova with the stellar wind from its optical component. This model is used to describe the intense X-ray outburst (the peak 3–20 keV flux was ~2 Crab) of the binary system CI Camelopardalis in 1998. According to our model, the stellar wind from the optical component heated by a strong shock wave produced when matter is ejected from the white dwarf as the result of a thermonuclear explosion on its surface is the emission source in the standard X-ray band. Comparison of the calculated and observed time dependences of the mean radiation temperature and luminosity of the binary system during its outburst has yielded very important characteristics of the explosion. We have been able to measure the velocity of the ejected matter immediately after the onset of the explosion for the first time: it follows from our model that the ejected matter had a velocity of ~2700 km s?1 even on 0.1–0.5 day after the outburst onset and it flew with such a velocity for the first 1–1.5 day under an external force, possibly, the radiation pressure from the white dwarf. Subsequently, the matter probably became transparent and began to decelerate. The time dependence of the mean radiation temperature at late expansion phases has allowed us to estimate the mass of the ejected matter, ~10?7–10?6 M . The mass loss rate in the stellar wind required to explain the observed peak luminosity of the binary system during its outburst has been estimated to be \(\dot M\) ~ (1 ? 2) × 10?6 M yr?1.  相似文献   
7.

A numerical–analytical approach is used to investigate irregular effects in oscillations of the Earth’s pole related to variations in the Chandler and annual components. An approach to studying oscillations in the motion of the Earth’s pole based on a joint analysis of the Chandler and annual components of this motion is proposed. A transformation to a new coordinate system in which the motion of the pole is synchronous with the precession of the lunar orbit can be found in this approach. Estimates of the precision of predictions of the coordinates of the Earth’s pole taking into account additional terms due to lunar perturbations are presented.

  相似文献   
8.
The main components ofthe Caspian Sea water balance and water level are assessed. Stochastic models of time series of the water balance components are proposed ustng morphometric dependences specified by creating and processing digital elevation models for the flooded areas. The sea level forecast is obtained by the method of simulation modeling based on algorithms for the generation of Markovian random sequences with non-Gaussian marginal distributions.  相似文献   
9.
Water Resources - A generalized step-by-step statistical method for calculating the maximal precipitation sums of low probability is proposed. The method is applied to the case of daily...  相似文献   
10.
Effects of fluctuational dissipative perturbations on the Earth’s polar motion due to random components of the centrifugal potential are studied using a numerical-analytical approach. A combined model for the polar fluctuations is used to take into account stochastic components of the polar tides. Fluctuations excited at frequencies close to the Chandler frequency are analyzed using observations of sea level and the gravitional acceleration. Equations describing the correlation characteristics of the polar motions are presented.  相似文献   
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