Physical and geometrical parameters of VCBS XIII: HIP 105947

The best physical and geometrical parameters of the main sequence close visual binary system(CVBS), HIP 105947, are presented. These parameters have been constructed conclusively using Al-Wardat’s complex method for analyzing CVBSs, which is a method for constructing a synthetic spectral energy distribution(SED) for the entire binary system using individual SEDs for each component star. The model atmospheres are in its turn built using the Kurucz(ATLAS9) line-blanketed plane-parallel models. At the same time, the orbital parameters for the system are calculated using Tokovinin’s dynamical method for constructing the best orbits of an interferometric binary system. Moreover, the mass-sum of the components, as well as the ?θ and ?ρ residuals for the system, is introduced. The combination of Al-Wardat’s and Tokovinin’s methods yields the best estimations of the physical and geometrical parameters. The positions of the components in the system on the evolutionary tracks and isochrones are plotted and the formation and evolution of the system are discussed.

A Revisit of the Phobos Events

The magnetic field disturbances detected by the Phobos-2 spacecraft in 1989 have been suggested to be caused by a ring of dust and/or gas emitted from the Martian moon,Phobos.The physical nature of these"Phobos events"is examined using results from related investigations over the last twenty years.It is concluded that there is no clear evidence at present to support the association of magnetic field disturbances in the solar wind with Phobos.The situation will be further clarified taking advantage of the multi-spacecraft observations of the Yinghuo-1(YH-1),Mars Express and MAVEN missions beginning in 2012.It is expected that many novel features of solar wind interaction with Phobos(and possibly also Deimos) itself will also be revealed.

A Brief Review for Quasi-Periodic Oscillations in Neutron-Star Low-Mass X-Ray Binaries

In accreting neutron star (NS) low-mass X-ray binaries (LMXBs), the turbulent flow in accretion disk may show magnetic structures. Its emission will vary in time due to inhomogeneous motions through and with the accretion flow. These emissions contribute to considerable X-ray variability on a wide range of timescales in all wavelengths, and down to milliseconds. In this article, we give a brief review for quasi-periodic oscillations (QPOs), one of a periodic X-ray variability, in NS/ LMXBs. Firstly, we give a brief introduction to NS/LMXBs and the fruitful QPO components. As an example, the energy dependence of normal branch oscillations in Scorpius X-1 is discussed. We mostly focus on the properties and mechanism of kilohertz QPOs—the fastest variability components that have the same order as the dynamical timescales of the innermost regions of accretion flow. Finally, we discuss the success and questions for theoretical interpretations and present the possible entry for investigation of nature of QPOs.