R. K. Zamanov

Hα observations of the γ-ray-emitting Be/X-ray binary LSI+61 ◦ 303: orbital modulation, disk truncation, and long-term variability ,

We report 138 spectral observations of the Hα emission line of the radio- andγ-ray-emitting Be/X-ray binary LSI+61 ◦ 303 obtained during the period of September 1998 ‐ January 2013. From measuring various Hα parameters, we found that the orbital modulation of the Hα is best visible in the equivalent width ratio EW(B)/EW(R), the equivalent width of the blue hump, and in the radial velocity of the central dip. The periodogram analysis confirmed that t he Hα emission is modulated with the orbital and superorbital periods. For the past 20 years the radius of the circumstellar disk is s imilar to the Roche lobe size at the periastron. It is probabl y truncated by a 6:1 resonance. The orbital maximum of the equivalent width of Hα emission peaks after the periastron and coincides on average with the X-ray andγ-ray maxima. All the spectra are available upon request from the authors and through the CDS.

Optical flickering of the recurrent nova RS Ophiuchi: amplitude–flux relation

We report observations of the flickering variability of the symbiotic recurrent nova RS Oph at quiescence in five bands (UBVRI). We find evidence of correlation between the peak-to-peak flickering amplitude (�F) and the average flux of the hot component (Fav). The correlation is highly significant with correlation coefficient 0.85 and p value � 10 20 . Combining the data from all wavebands, we find a dependence of

Optical spectroscopy of Be/gamma-ray binaries

We report optical spectroscopic observations of the Be/gamma-ray binaries LSI+61303, MWC 148 and MWC 656. The peak separation and equivalent widths of prominent emission lines (H-alpha, H-beta, H-gamma, HeI, and FeII) are measured. We estimated the circumstellar disc size, compared it with separation between the components, and discussed the disc truncation. We find that in LSI+61303 the compact object comes into contact with the outer parts of the circumstellar disc at periastron, in MWC 148 the compact object goes deeply into the disc during the periastron passage, and in MWC 656 the black hole is accreting from the outer parts of the circumstellar disc along the entire orbit. nThe interstellar extinction was estimated using interstellar lines. The rotation of the mass donors appears to be similar to the rotation of the mass donors in Be/X-ray binaries. We suggest that X-ray/optical periodicity of about 1 day deserves to be searched for.

Connection between orbital modulation of Hα and gamma-rays in the Be/X-ray binary LS I+61°303

We studied the average orbital modulation of various parameters (γ-ray flux, Hα emission line, optical V band brightness) of the radioand γ-ray emitting Be/ X-ray binary LS I+61 ◦ 303. Using the Spearman rank correlation test, we found highly significant correlations between the orbital variability of the equivalent width of the blue hump of the Hα and Fermi-LAT flux with a Spearman p-value ∼2 × 10 −5 , and the equivalent widths ratio EWB/EWR and Fermi-LAT flux with p-value ∼9 × 10 −5 . We also found a significant anticorrelation between Fermi-LAT flux and V band magnitude with a p-value ∼7 × 10 −4 . All these correlations refer to the average orbital variability, and we conclude that the Hα and γ-ray emission processes in LS I+61 ◦ 303

Orbital parameters of the high-mass X-ray binary 4U 2206+54†

We present new radial velocities of the high-mass X-ray binary star 4U 2206+54 based on optical spectra obtained with the Coude spectrograph at the 2 m RCC telescope of the Rozhen National Astronomical Observatory, Bulgaria in the period November 2011–July 2013. The radial velocity curve of the He I δ6678 A line is modeled with an orbital period Porb = 9.568 d and an eccentricity of e = 0.3. These new measurements of the radial velocity resolve the disagreements of the orbital period discussions. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Flickering of accreting white dwarfs: the remarkable amplitude–flux relation and disc viscosity

We analyze optical photometric data of short term variability (flickering) of accreting white dwarfs in cataclysmic variables (KR Aur, MV Lyr, V794 Aql, TT Ari, V425 Cas), recurrent novae (RS Oph and T CrB) and jet-ejecting symbiotic stars (CH Cyg and MWC 560). We find that the amplitude-flux relationship is visible over four orders of magnitude, in the range of fluxes from

AG Pegasi – now a classical symbiotic star in outburst?

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Orbital eccentricity of the symbiotic star MWC 560

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Discovery of optical flickering from the symbiotic star EF Aquilae

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Rotation of the Mass Donors in High-mass X-ray Binaries and Symbiotic Stars

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