Search

We present a high-cadence time series of spectroscopic observations of the Hα emission line profile obtained during the egress and total eclipse phases of the M supergiant binary VV Cephei (M2 Iab + B0-2 V) for the 2017-2018 eclipse. Medium-resolution spectroscopy, obtained at an almost nightly cadence by the ARAS Spectroscopy Group from April 2017 through June 2018, has been used to construct a time-series of equivalent widths (EWs) of the Hα emission line flux. The peak fluxes of the blue (V) component and the red (R) component relative to the continuum, as well as their ratio, V/R, have also been found. We report on a new 43.5-day periodic variation in the Hα emission that is present throughout the entire time series and, in particular, persists through mid-eclipse. [ABSTRACT FROM AUTHOR]

The article offers information on VV Cep, a long-term binary system comprised of an M2Iab primary star and an early B secondary star, it mentions of investigation of the binary system VV Cep in very different aspects and presents a table on period analysis of of VV Cep.

The article presents a study which monitors the Hα emission strength and photometric magnitude of γ Cas. Methods and instruments used in the spectroscopic observations and the possible correlation between Hα equivalent width and visual (V) magnitude are offered. Results which determined the non-linear relationship between the H&# 945; EW and the V magnitude and long-term variations of Cas in the visual region are discussed.

Aims. The work is aimed at studying the circumstellar disk of the bright classical binary Be star π Aqr. Methods. We analysed variations of a double-peaked profile of the Hα emission line in the spectrum of π Aqr that was observed in many phases during ∼40 orbital cycles in 2004-2013. We applied the discrete Fourier transform (DFT) method to search for periodicity in the peak intensity ratio (V/R). Doppler tomography was used to study the structure of the disk around the primary. Results. The dominant frequency in the power spectrum of the Hα V/R ratio is 0.011873 day-1, which corresponds to a period of 84.2(2) days and agrees with the earlier determined orbital period of the system, Porb = 84.1 days. The V/R shows a sinusoidal variation that is phase-locked with the orbital period. Doppler maps of all our spectra show a non-uniform structure of the disk around the primary: a ring with the inner and outer radii at Vin ≈ 450 km s-1 and Vout ≈ 200 km s-1, respectively, along with an extended stable region (spot) at Vx ≈ 225 km s-1 and Vy ≈ 100 km s-1. The disk radius of ≈65 R☉ = 0.33 AU was estimated by assuming Keplerian motion of a particle on a circular orbit at the disk's outer edge. [ABSTRACT FROM AUTHOR]