Assessment of landslide susceptibility using DBSCAN-AHD and LD-EV methods

Landslide susceptibility assessment plays a vital role in understanding landslide information in advance and taking preventive as well as control measures.The n...     

Energetics of galactic nuclei

A model of compact galactic nuclei in statistical equilibrium was developed in [L. Sh. Grigorian and G. S. Sahakian, Astrofizika (in press)]. It was shown that they should consist predominantly of neutron stars (pulsars) and white dwarfs. The problem of the energy reserves of galactic nuclei is discussed in terms of this concept. The mechanism of conversion of a white dwarf into a neutron star due to the accretion of interstellar matter is considered. This means that a galactic nucleus has an energy reserve of some 5·10⁶⁰ N₈ erg (N is the number of stars in the nucleus). It is shown that galactic nuclei are powerful sources of hard γ radiation [power L » 2·10⁴⁴µ₃₀N₈(Ω/50)^17/7 erg/sec, where µ is the magnetic moment and Ω is the angular rotation rate of a neutron star ] due to curvature radiation from relativistic electron fluxes flowing along channels of open magnetic field lines of pulsars. The x-ray and ultraviolet emission are due to synchrotron emission from the same electron fluxes in the magnetic field of the galactic nucleus (L » 10⁴²-10⁴⁴ erg/sec). The optical (visible and infrared) and radio emission are due to bremsstrahlung from electrons in the interstellar medium [L » 6·10⁴⁶N ₈ ² (5/R_pc)³ erg/sec, where R is the radius of the galactic nucleus]. An equation is obtained for the magnetic moment of a pulsar: µ ≈ 3.4·10^-5L_γP^17/7, where P is the pulsar’s period and L_03B3; is the luminosity of the pulsar’s y radiation.     

Investigations of space debris at Terskol observatory

Within the framework of the “Astronomy in the Elbrus Region” international program, investigations of space debris objects using optical measurements are carried out at the observation complex of the Zeiss-2000 telescope (developed by the International Center for Astronomical and Medico-Ecological Research, National Academy of Sciences, Ukraine) at Terskol Observatory. The objectives of this study are to detect, catalog, and determine the physical characteristics of small-sized space debris fragments, maintain orbit catalogs, and investigate the influence of nongravitational perturbations on the orbital motion and the evolution of orbits of these fragments.     

Variability of Circumstellar Emission from Dust Envelopes Around Carbon Stars

The main constituents of the dust, produced around late-type carbon stars, are thought to be carbon and silicon carbide (SiC), although their exact nature is not yet well established. This subject has been addressed by several authors and good fits of a large number of IRAS sources (chosen among the carbon stars exhibiting the SiC feature at about 11.3 m) were obtained. In this work we use the same procedure on a limited number of objects, of the same type, taking into account the variability of such sources and the changes induced in their IR spectra. For this purpose, the chosen stars have been observed with a spectral resolution higher than that available for the IRAS data (/ 50), using the CGS3 instrument of the UKIRT telescope, both in the low ( / 160) and in the high ( / 500) resolution configuration. The results are discussed and some preliminary conclusions are drawn.     

Large-Scale Electric Fields in Solar Flare Regions

A method of separating electric field in the flare region in the potential and vortex (induced) parts is discussed. According to the proposed model, the motion of flare ribbons from the central line of the flare region is caused by the vortex component of the coronal electric field, while the motion of bright spots within the flare region towards the central line is driven by the potential component of that field. The intensity of both the components of the flare region electric field is estimated to equal approximately 1–3 V cm^–1, which provides the input of the electromagnetic energy into the active region at a rate of about 10¹⁰ erg cm^–2 s^–1.     

Carbon Abundance in Early B-Stars. I. NLTE Calculations for ΓPeg.

NLTE calculations of carbon abundance in Peg atmosphere revealed a slight deficiency of this element ([C/H] =–0.25). A short discussion of this result is given. The list of CII that could be used for LTE calculation of carbon abundance in hot stars is presented.