Related papers: Is the semi-regular variable RU Vulpeculae undergo…
For the carbon AGB star R Sculptoris, the uncertain distance significantly affects the interpretation of observations regarding the evolution of the stellar mass loss during and after the most recent thermal pulse. We aim to provide a new,…
Nova-like variables are high-accretion-rate cataclysmic variables (CVs) that, in contrast to dwarf novae, do not undergo outbursts caused by thermal-viscous instability. However, a small group of nova-likes, classified as AH Pic-type stars,…
Stellar evolution computations were carried out for stars with a main sequence mass $M_\mathrm{ZAMS}=0.86M_\odot$ and initial metal abundance $Z=0.003$ and $Z=0.004$. Selected models of evolutionary sequences were used for calculation of…
As part of our continuing study of light variability in proto-planetary nebulae (PPNe), we present the results from a long-term study of nine southern hemisphere objects. We have monitored their light variations over a nine-year interval…
Context. The post-main-sequence evolution of massive stars remains poorly understood, particularly for blue supergiants. These objects play a crucial role in the dynamical and chemical evolution of galaxies and exhibit pronounced…
We have analysed the photometry of 924 type II Cepheids from the Galactic bulge observed by the Optical Gravitational Lensing Experiment. Our goal was to detect and analyse various dynamical phenomena, including, e.g. multi-mode pulsation,…
We analysed the planetary nebula Hen 2-260 using optical spectroscopy and photometry. We compared our observations with the data from literature to search for evolutionary changes. The nebular line fluxes were modelled with the Cloudy…
We give a status report of convective Cepheid and RR Lyrae model pulsations. Some striking successes can be reported, despite the use of a rather simple treatment of turbulent convection with a 1D time-dependent diffusion equation for the…
So far the highly unstable phase of luminous blue variables (LBVs) has not been understood well. It is still uncertain why and which massive stars enter this phase. Investigating the variabilities by looking for a possible regular or even…
RR Lyr is one of the most studied variable stars. Its light curve has been regularly monitored since the discovery of the periodic variability in 1899. Analysis of all observed maxima allows us to identify two primary pulsation states…
13\,Tau is a rarely studied bright B9V type star ({\sl V} = 5.68 mag), which shows a weak and double-peaked H{$\alpha$} emission profile in its spectra. In this study, we presented high-precision photometric data of 13\,Tau taken by the…
The light curve of a blue variable in the MACHO LMC database (FTS ID 78.5979.72) appeared nearly unvarying for ~4 years (quasi-flat segment) but then rapidly changed to become periodic with noisy minima for the remaining 4 years (periodic…
We obtained a series of more than two hundred R-band CCD images for the crowded central (115"x77") region of the metal-poor globular cluster M15 with an angular resolution of 0.5"-0.9" in most images. Optimal image subtraction was used to…
We present the results of UBVJHKLM photometry of R CrB spanning the period from 1976 to 2001. Studies of the optical light curve have shown no evidence of any stable harmonics in the variations of the stellar emission. In the L band we…
The light curves of 50 RRab (RR0) stars in M5 collected in Paper I are investigated to detect Blazhko modulation. 18 Blazhko stars are identified, and modulation is suspected in two additional cases. The mean pulsation period of Blazhko…
To investigate the asymptotic giant branch (AGB) population in the Galactic halo, we search for pulsating AGB stars at a heliocentric distance over 50kpc. Our research is based on the Catalina Southern Survey (CSS) catalogue of variables,…
In recent years, much studies have focused on determining the origin of the large-scale line-profile and/or photometric patterns of variability displayed by some apparently single Wolf-Rayet stars, with the existence of an unseen…
The Wolf-Rayet star WR 46 is known to exhibit a very complex variability pattern on relatively short time scales of a few hours. Periodic but intermittent radial velocity shifts of optical lines as well as multiple photometric periods have…
We present a search for long-period variable (LPV) stars among giant branch stars in M15 which, at [Fe/H] ~ -2.3, is one of the most metal-poor Galactic globular clusters. We use multi-colour optical photometry from the 0.6-m Keele Thornton…
Context. Betelgeuse is a red supergiant (RSG) that is known to vary semi-regularly on both short and long timescales. The origin of the short period of Betelgeuse has often been associated to radial pulsations but could also be due to the…