Related papers: The enigmatic B[e] star Hen 2-90 -- an interacting…
We performed the optical spectroscopy of 16 classical Be stars in 11 open clusters older than 100 Myr. Ours is the first spectroscopic study of classical Be stars in open clusters older than 100 Myr. We found that the H alpha emission…
In the attempt to shed new light on the lambda Boo phenomenon we analyzed the astrometric, photometric and spectroscopic characteristics of stars out of a list of recently selected lambda Boo candidates. We show that the class is still…
Classical barium stars are binary systems which consist of a late-type giant enriched in carbon and slow neutron capture (s-process) elements and an evolved white dwarf (WD) that is invisible at optical wavelengths. The youngest observed…
The atmosphere of the extremely high-velocity (530-920 km/s) early B-type star HD271791 is enriched in $\alpha$-process elements, which suggests that this star is a former secondary component of a massive tight binary system and that its…
Double-lined spectroscopic binaries which are also eclipsing provide the most accurate stellar data, and are consequently of first importance to improve stellar evolution modelling. While the mass and radius of each component of detached…
The study of planetary nebulae provides important constraints for many aspects of stellar and Galactic evolution. Hen 2-108 is a poorly known planetary nebula with a slight elliptical morphology and a peculiar central star (CS), which has…
Among the emission-line stars, the classical Be stars known for their extreme properties are remarkable. The Be stars are B-type main sequence stars that have displayed at least once in their life emission lines in their spectrum. Beyond…
Beta Cen is a bright Beta Cephei variable and has long been suspected to be a binary. Here we report interferometric observations with the 3.9-m Anglo-Australian Telescope at a single epoch which show the star to be a binary with components…
The contact phase represents a crossroad in the evolution of massive binary stars. Depending on the internal physics, the predicted end products can vary greatly including various exotic objects such as Be stars, magnetic massive stars,…
The supergiant High Mass X-ray Binary IGR J16318-4848 was the first source detected by the INTEGRAL satellite in 2003 and distinguishes itself by its high intrinsic absorption and B[e] phenomenon. It is the perfect candidate to study both…
We present highlights and an overview of 20 FUSE and HST/STIS observations of the bright symbiotic binary EG And. The main motivation behind this work is to obtain spatially-resolved information on an evolved giant star in order to…
Brightening of Hen 3-860, previously classified as an H$\alpha$ emitter, was detected by the ASAS-SN survey at the end of the year 2016. We have obtained the first spectroscopic observations of the transient and supplemented them with…
We present the results of optical and near-IR spectroscopic and near-IR photometric observations of the emission-line stars Hen3-298 and Hen3-303. Strong emission in the H-alpha line is found in both objects. The presence of Fe II and [O I]…
V503 Her was previously proposed as an eclipsing symbiotic candidate based on photometric behavior and spectroscopic appearance indicating the composite optical spectrum. To investigate its nature, we analyzed long-term photometric…
We identified a new post-interaction binary, HIP 15429, consisting of a stripped star and a recently formed, rapidly rotating Be star companion ($v \sin i \approx 270$ km/s) sharing many similarities with recently identified bloated…
The theory of binary evolution predicts that many massive stars should lose their hydrogen-rich envelopes via interaction with a companion -- revealing hot helium stars with masses of $\sim$2--8M$_{\odot}$. However, only one candidate…
The nature of non-variable high-excitation emission lines detected in the optical spectra of normal late-B type and chemically peculiar HgMn and PGa stars is still poorly understood. To better understand the origin of the weak emission…
The intriguing binary LS V +22 25 (LB-1) has drawn much attention following claims of it being a single-lined spectroscopic binary with a 79-day orbit comprising a B-type star and a ~70 Msun black hole. Recent analyses have implied that the…
A brief summary of properties of the contact binaries is presented, with the goal to stress the unsolved problems of their formation and evolution as well as their potential contribution to studies of Galactic stellar populations. The first…
There exists a number of astronomical spectral phenomena that have remained unidentified after decades of extensive observations. The diffuse interstellar bands, the 220 nm feature, unidentified infrared emission bands, extended red…