ﻻ يوجد ملخص باللغة العربية
We have investigated the influence of X-ray irradiation on the vertical structure of the outer accretion disk in low-mass X-ray binaries by performing a self-consistent calculation of the vertical structure and X-ray radiation transfer in the disk. Penetrating deep into the disk, the field of scattered X-ray photons with energy $Egtrsim10$,keV exerts a significant influence on the vertical structure of the accretion disk at a distance $Rgtrsim10^{10}$,cm from the neutron star. At a distance $Rsim10^{11}$,cm, where the total surface density in the disk reaches $Sigma_0sim20$,g,cm$^{-2}$, X-ray heating affects all layers of an optically thick disk. The X-ray heating effect is enhanced significantly in the presence of an extended atmospheric layer with a temperature $T_{atm}sim(2div3)times10^6$,K above the accretion disk. We have derived simple analytic formulas for the disk heating by scattered X-ray photons using an approximate solution of the transfer equation by the Sobolev method. This approximation has a $gtrsim10$,% accuracy in the range of X-ray photon energies $E<20$,keV.
In the last decade, X-ray spectroscopy has enabled a wealth of discoveries of photoionised absorbers in X-ray binaries. Studies of such accretion disc atmospheres and winds are of fundamental importance to understand accretion processes and possible
We present new Chandra observations of the outer halo of the giant elliptical galaxy NGC 4472 (M49) in the Virgo Cluster. The data extend to 130 kpc (28), and have a combined exposure time of 150 ks. After identifying optical counterparts using the N
We search the literature for reports on the spectral properties of neutron-star low-mass X-ray binaries when they have accretion luminosities between 1E34 and 1E36 ergs/s. We found that in this luminosity range the photon index (obtained from fitting
We have developed a stellar wind model for OB supergiants to investigate the effects of accretion from a clumpy wind on the luminosity and variability properties of High Mass X-ray Binaries. Assuming that the clumps are confined by ram pressure of th
We report measurements of parallax and proper motion for four 22 GHz water maser sources as part of VERA Outer Rotation Curve project. All sources show Galactic latitudes of $>$ 2$^{circ}$ and Galactocentric distances of $>$ 11 kpc at the Galactic lo