Vol 74, No 1 (2019)

We present the results of RATAN-600 observations of a sample of strong (S > 0.5 Jy) flatspectrum sources from the JVAS catalog at 10. ◦ 5–18◦ (J2000) declinations in 2015, 2016, and 2017 at the frequencies of 2.3, 4.7, 8.2, 11.2, and 21.7 GHz. We have obtained spectra of all 45 sources and isolated sources with significant variations. Four sources were found for the first time to have variations with typical time scales of 8 to 35 days. Spectra of the variable components have also been obtained.

Based on the data of spectral monitoring of the yellow hypergiant V509 Cas performed in 1996–2018 at the 6-m telescope with the spectral resolution of R ≥ 60 000, we studied in detail its kinematic state at various levels of extended atmosphere. No signs of presence of a companion were found. An agreement of radial velocities measured on the permitted and forbidden emissions of metal ions, as well as their strict temporal stability led to the choice of the systemic velocity of the star Vsys = −63 km s⁻¹. The position of forbidden [NII] emissions forming in the circumstellar medium is strictly stable and is systematically shifted by −6 kms⁻¹ relative to the metal ion emissions. A conclusion on the variation of the [NII] emission halfwidths and intensities (the lines have become narrower and more intense) is made after the observations in 1996 and over the next 22 years of observations, these parameters did not vary. The velocities measured from the shortwave Fe II (42) absorption components are located in a narrow interval of V_r = [−84;−87] kms⁻¹, which indicates the stability of expansion of the upper layers of the atmosphere. The overall atmosphere of the hypergiant is stable, excluding the layers close to the photosphere. The velocity variability in range of V_r = [−52;−71] km s⁻¹, identified by the positions of strong metal ion absorption cores may be a manifestation of pulsations in deep atmospheric layers, where this type of lines are formed.

The paper presents the results of determination of fundamental parameters (effective temperature, surface gravity, luminosity, mass, radius, rotation velocity, and radial velocity) for 146 stars observed at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the Main Stellar Spectrograph during 2009–2011; 124 of the stars are magnetic or potentially magnetic objects. We obtained and analyzed at least 500 pairs of circularly-polarized-emission spectra. Various methods and approaches were used in estimating the fundamental parameters.

We have modeled the cyclotron spectra and photopolarimetric data of polar CRTS CSS081231 J071126+440405. A series of spectra of the polar were obtained in the intermediate brightness state spanning an orbital period. Modeling spectra allowed us to determine the magnetic field strength in the vicinity of both magnetic poles of the white dwarf: B₁ = 38 MG and B₂ = 51 MG. We obtained a temperature estimate for the accretion spots near both magnetic poles of the white dwarf. The estimate for the first spot is kT ~ 20–30 keV, whereas the second spot turned out to be cooler by about 10 keV. An analysis of the light curves and polarization of the polar obtained in the low state shows that the interaction of the accretion stream with the star’s atmosphere occurs close (within Δθ = 10◦) to the magnetic pole.