On the possible nature of Bp-Ap Stars: an application to HD101065 and HR465

We have proposed the new explanation of some magnetic chemically peculiar (MCP) stars anomalies, which is based on assumption that such stars can be the close binary systems with a secondary component being neutron star. Within this hypothesis one can naturally explain the main anomalous features of MCP stars: first of all, an existence of the short-lived radioactive isotopes detected in some stars (like Przybylski's star and HR465), and some others peculiarities (e.g. the behavior of CU Vir in radio range, the phenomenon of the roAp stars).Comment: 5 pages, 5 figure

About the chemical composition of delta Scuti - the prototype of the class of pulsating variables

We present chemical abundances in the photosphere of $\delta$ Scuti -- the prototype of the class of pulsating variables -- determined from the analysis of a spectrum obtained at Terskol observatory 2 meter telescope with resolution $R=52,000$, signal to noise ratio 250. VLT and IUE spectra were used also . Abundance pattern of \dsct consists of 49 chemical elements. The abundances of Be, P, Ge, Nb, Mo, Ru, Er, Tb, Dy, Tm, Yb, Lu, Hf, Ta, Os, Pt, Th were not investigated previously. The lines of third spectra of Pr and Nd also are investigated for the first time. The abundances of heavy elements show the overabundances with respect to the Sun up to 1 dex. The abundance pattern of \dsct is similar to that of Am-Fm stars.Comment: 8 pages, 2 figures, subm. to Proc. of IAU Symp. 22

Some evolutionary aspects of the binary stellar systems containing neutron star

The obvious lack of the binary stellar systems that contain neutron stars (NS) is observed at present. Partly it is caused by the fact that it is very difficult to detect neutron star in a binary system if this relativistic component does not manifest itself as a radio pulsar. Among 1879 pulsars that are listed in the ATNF pulsar catalogue, only 141 pulsars are known to be the companions in binary systems. Only 81 objects having median mass estimation of more than 0.2 $M_{\odot}$ constitute the binary systems with pulsars. Nevertheless, such systems should be much more numerous and their investigation is of the great interest because thier structure and evolution can certainly help in our understanding of many unique properties that are seen in some stars.Comment: Accepted to published in the Odessa Astronomical Publications, 2012, vol. 25/1, p.35-3

The chemical composition of a mild barium star HD202109

We present the result of chemical abundances of a mild barium star HD202109 (zeta Cyg) determined from the analysis of spectrum obtained by using a 2-m telescope at the Peak Terskol Observatory and a high-resolution spectrometer with R=80,000, signal to noise ratio >100. We also present the atmospheric parameters of the star determined by using various methods including iron-line abundance analysis. For line identifications, we use whole-range synthetic spectra computed by using the Kurucz database and the latest lists of spectral lines. Among the determined abundances of 51 elements, those of P, S, K, Cu, Zn, Ge, Rb, Sr, Nb, Mo, Ru, Rh, Pd, In, Sm, Gd, Tb, Dy, Er, Tm, Hf, Os, Ir, Pt, Tl, and Pb have not been previously known. Under the assumption that the overabundance pattern of Ba stars is due to wind-accretion process, adding information of more element abundances enables one to show that the heavy element overabundances of HD202109 can be explained with the wind accretion scenario model.Comment: 10 pages, Accepted by Astronomy and Astrophysic

Some Statistical Picture of Magnetic CP Stars Evolution

We discuss some statistical results on the evolution of magnetic CP stars in the framework of the supposition about their binary nature.Comment: 3 pages, 3 figure

Atmospheric chemical composition of the "twin" components of equal mass in the CP SB2 system 66 Eri

We determine the atmospheric chemical composition of the components of the CP SB2 system 66 Eri with approximately equal masses (MA/MB = 0.97) by using two CCD echelle spectra of the star. These spectra have been taken with the 1-m telescope at Special Astrophysical Observatory with a spectral resolution of 36000 and a signal-to-noise ratio no less than 100 in the wavelength range 4385-6695 Å. The model-atmosphere parameters for the components are estimated by analyzing all available photometric and spectrophotometric data and the equivalent widths of iron lines. For components A and B, we have obtained TeffA = 11100 K, TeffB = 10900 K, loggA = 4.25, loggB = 4.25, VturbA = 0.9 km s-1, VturbB = 0.7 km s-1, and v siniA,B = 17 km s-1. The derived projected rotational velocities of the components, together with the HIPPARCOS parallax and photometric observations, show that their rotation may be synchronized with the orbital period. The star exhibits a considerable infrared excess at wavelengths longer than 25 μm. The synthetic-spectrum and model-atmosphere methods are used to determine the atmospheric abundances of 26 chemical elements in component B and 15 chemical elements in component A. The components differ markedly in chemical composition. The peculiar component B exhibits no chemical anomalies that are typical of the Hg-Mn group, such as an underabundance of He and Al and an enhancement of P and Ga, but shows large heavy-element overabundances reaching 4-5 dex. The atmosphere of component A also exhibits moderate overabundances of Mn and Ba, but no lines of other heavy elements have been found in its spectrum. However, an estimate of the upper limit on their abundances does no rule out small heavy-element Noverabundances in the atmosphere of component A either. 66 Eri is the first and the only close SB2 system with CP non-Hg-Mn components studied to date

SOME EVOLUTIONARY ASPECTS OF THE BINARY STELLAR SYSTEMS CONTAINING NEUTRON STAR

ABSTRACT. The obvious lack of the binary stellar systems that contain neutron stars (NS) is observed at present. Partly it is caused by the fact that it is very dicult to detect neutron star in a binary system if this relativistic component does not manifest itself as a radio pulsar. Among 1879 pulsars that are listed in the ATNF pulsar catalogue, only 141 pulsars are known to be the companions in binary systems. Only 81 objects having median mass estimation of more than 0.2 M ⊙ constitute the binary systems with pulsars. Nevertheless, such systems should be much more numerous and their investigation is of the great interest because thier structure and evolution can certainly help in our understanding of many unique properties that are seen in some stars