Related papers: Variability of Be Stars in Southern Open Clusters
Recent observational studies suggest that Be stars most likely are formed through the process of mass transfer in binary systems. In view of the wide consensus that the origin of the magnetic field in stars with radiative envelopes involves…
The light curves of 252 B-star candidates in the Kepler data base are analyzed in a similar fashion to that done by Balona et al. (2011) to further characterize B star variability, increase the sample of variable B stars for future study,…
Recent papers published in the last years contributed to resolve the enigma on the hypothetical Be nature of the hot pulsating star $\beta$ Cep. This star shows variable emission in the H$\alpha$ line, typical for Be stars, but its…
Multi-color OGLE survey light curves of about 20 years duration are analyzed for about 3000 classical Be stars in the Large and Small Magellanic Clouds (LMC, SMC) in order to study the properties and variability. Each light curve was…
Aims: This paper presents a new homogeneous catalogue of blue straggler stars (BSS) in Galactic open clusters. Methods: Photometric data for 216 clusters were collected from the literature and 2782 BSS candidates were extracted from 76 of…
Since Be stars belong to the high velocity tail of a single B star velocity distribution, the appearance of the Be phenomenon must be independent of the stellar mass. In the present paper we show that the shape of the distribution of the…
In recent years the idea, first formulated many decades ago, that the Be phenomenon could be causally related to the duplicity of Be stars, has been repeatedly reconsidered from various perspectives. It is important, therefore, to have…
We analysed ASAS-3 photometry of bright early-type stars with the goal of finding new Beta Cephei stars. We were particularly interested in stars that would be good for seismic analysis, i.e., stars that (i) have a large number of excited…
As many as 10\% of OB-type stars have global magnetic fields, which is surprising given their internal structure is radiative near the surface. A direct probe of internal structure is pulsations, and some OB-type stars exhibit pressure…
We present a comprehensive photometric analysis of a young open cluster NGC 1960 (M36) along with the long-term variability study of this cluster. Based on the kinematic data of Gaia DR2, the membership probabilities of 3871 stars are…
We present uvby-beta CCD photometry of the field of the open cluster NGC 1893. Our photometry is deep enough to cover the complete main sequence B spectral type. We identify ~50 very likely members of the cluster down to spectral type…
There are nine metal-deficient stars that have Li abundances well below the Li plateau that is defined by over 100 unevolved stars with temperatures above 5800 K and values of [Fe/H] $<$ $-$1.0. Abundances of Be have been determined for…
We continue our survey for magnetic chemically peculiar (CP2) stars in galactic open clusters to shed more light on their origin and evolution. To study the group of CP2 stars, it is essential to find these objects in different galactic…
We have analysed the photometric data obtained with the STEREO spacecraft for 558 non-magnetic chemically peculiar (CP) stars to search for rotational and pulsational variability. Applying the Lomb-Scargle and the phase dispersion…
We present preliminary photometric results of a monitoring study of the open cluster NGC 2660 as part of the EXPLORE/OC project to find planetary transits in Galactic open clusters. Analyzing a total of 21000 stars (3000 stars with…
It is well known that massive O-stars are frequently (if not always) found in binary or higher-order multiple systems, but this fact has been less robustly investigated for the lower mass range of the massive stars, represented by the…
About 22000 Kepler stars and nearly 60000 TESS stars from sectors 1-24 have been classified according to variability type. A large proportion of stars of all spectral types appear to have periods consistent with the expected rotation…
Classical Be stars are fast rotating, near main sequence B-type stars. The rotation and the presence of circumstellar discs profoundly modify the observables of active Be stars. Our goal is to infer stellar and disc parameters, as well as…
Classical Be stars are introduced as object class and their particular potential for space based photometry is highlighted. A brief summary of the various types of variability observed in Be stars makes clear that an interpretation of every…
We present results of a CCD variability search in the field of the young open cluster NGC 6834. We discover 15 stars to be variable in light. The brightest, a multiperiodic Gamma Doradus-type variable is a foreground star. The eight fainter…