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Context. Blue supergiant stars are known to display photometric and spectroscopic variability that is suggested to be linked to stellar pulsations. Pulsational activity in massive stars strongly depends on the star's evolutionary stage and is assumed to be connected with mass-loss episodes, the appearance of macroturbulent line broadening, and the formation of clumps in the wind. Aims. To investigate a possible interplay between pulsations and mass-loss, we carried out an observational campaign of the supergiant 55 Cyg over a period of five years to search for photospheric activity and cyclic mass-loss variability in the stellar wind. Methods. We modeled the H, He i, Si ii, and Si iii lines using the nonlocal thermal equilibrium atmosphere code FASTWIND and derived the photospheric and wind parameters. In addition, we searched for variability in the intensity and radial velocity of photospheric lines and performed a moment analysis of the line profiles to derive frequencies and amplitudes of the variations. Results. The Hα line varies with time in both intensity and shape, displaying various types of profiles: P Cygni, pure emission, almost complete absence, and double or multiple peaked. The star undergoes episodes of variable mass-loss rates that change by a factor of 1.7-2 on different timescales. We also observe changes in the ionization rate of Si ii and determine a multiperiodic oscillation in the He i absorption lines, with periods ranging from a few hours to 22.5 days. Conclusions. We interpret the photospheric line variations in terms of oscillations in p-, g-, and strange modes. We suggest that these pulsations can lead to phases of enhanced mass loss. Furthermore, they can mislead the determination of the stellar rotation. We classify the star as a post-red supergiant, belonging to the group of α Cyg variables. [ABSTRACT FROM AUTHOR]

We present spectroscopic and photometric analysis of the quintuple star HD 86222 with an eclipsing component. Until now three visual components A, B, and C of this multiple star were known. Four components in the A/B pair were detected during the examination of the cross correlation functions obtained from the spectra. We noticed that the visual components A and B, separated by 0".5, are in fact two binary stars - one eclipsing pair and one spectroscopic system. The pair with higher radial velocity amplitude corresponds to the eclipsing period. Photometric and spectroscopic observations of the eclipsing binary enable us to obtain the Wilson-Devinney model. The masses of this pair are M1 = 1.29 ±0.09 M☉ and M2= 1.33 ±0.09 M☉, respectively. The radii, slightly higher than for the main sequence stars, are R1 = 1.35 ±0.01 R☉ and R2= 1.36 ±0.01 R☉, respectively. The main parameters of the spectroscopic binary are also estimated, but they must be confirmed by future observations because of the uncertainty of the period. The farthest star named C, is 15 arc seconds from the main A and B components. Assuming that this object is gravitationally connected with the A and B binary pairs, HD 86222 has at least five components. [ABSTRACT FROM AUTHOR]

First spectroscopic and new photometric observations of the eclipsing binary FM Leo are presented. The main aims were to determine the orbital and stellar parameters of the two components and their evolutionary stage. First spectroscopic observations of the system were obtained with the David Dunlap Observatory and Poznań Spectroscopic Telescope spectrographs. The results of the orbital solution from radial velocity curves are combined with those derived from the light-curve analysis ( V-band photometry from the All Sky Automated Survey and supplementary observations of eclipses with the 1 and 0.35 m telescopes) to derive orbital and stellar parameters.jktebop, Wilson–Devinney binary modelling codes and a two-dimensional cross-correlation method were applied for the analysis. We find the masses to be and and the radii to be and for primary and secondary stars, respectively. The evolutionary stage of the system is briefly discussed by comparing physical parameters with current stellar evolution models. We find that the components are located at the main sequence, with an age of about 3 Gyr. [ABSTRACT FROM AUTHOR]

V440 Per is a Population I Cepheid with a period of 7.57 d and low-amplitude, almost sinusoidal light and radial velocity curves. With no reliable data on the first harmonic, its pulsation mode identification remained controversial. We obtained a radial velocity curve of V440 Per with our new high-precision and high-throughput Poznań Spectroscopic Telescope. Our data reach an accuracy of 130 m s−1 per individual measurement and yield a secure detection of the first harmonic with an amplitude of . The velocity Fourier phase φ21 of V440 Per is inconsistent at the 7.25σ level with those of fundamental-mode Cepheids, implying that the star must be an overtone Cepheid, as originally proposed by Kienzle et al. Thus, V440 Per becomes the longest-period Cepheid with securely established overtone pulsations. We show that a convective non-linear pulsation hydrocode can reproduce the Fourier parameters of V440 Per very well. The requirement to match the observed properties of V440 Per constrains the free parameters of the dynamical convection model used in the pulsation calculations, in particular the radiative loss parameter. [ABSTRACT FROM AUTHOR]

The Global Astronomical Telescope System is a project managed by the Astronomical Observatory Institute of Adam Mickiewicz University in Poznań (Poland) and it is primarily intended for stellar medium/high resolution spectroscopy. The system will be operating as a global network of robotic telescopes. The GATS consists of two telescopes: PST 1 in Poland (near Poznań) and PST 2 in the USA (Arizona). The GATS project is also intended to cooperate with the BRITE satellites and supplement their photometry with spectroscopic observations. [ABSTRACT FROM PUBLISHER]