Related papers: Pulsating B and Be stars in the Magellanic Clouds
Stellar pulsations in main-sequence B-type stars are driven by the $\kappa$-mechanism due to the Fe-group opacity bump. The current models do not predict the presence of instability strips in the B spectral domain at very low metallicities.…
We present here the results of our research for B-type pulsators in low metallicity environments, searching for short-term periodic variability in a large sample of B and Be stars in the Magellanic Clouds (MC), for which the fundamental…
Context: Stellar pulsations in main-sequence B-type stars are driven by the kappa-mechanism due to the Fe-group opacity bump. The current models do not predict the presence of instability strips in the B spectral domain at very low…
The B-type pulsators known as \beta Cephei and Slowly Pulsating B (SPB) stars present pulsations driven by the \kappa mechanism, which operates thanks to an opacity bump due to the iron group elements. In low-metallicity environments such…
Massive B type pulsators such as beta Cep and slowly pulsating B (SPB) stars pulsate due to layers of increased opacity caused by partial ionization. The increased opacity blocks the energy flux to the surface of the stars which causes the…
We present new results obtained with the VLT GIRAFFE for a large sample of B and Be stars belonging to the Magellanic Clouds, i.e. at low metallicity. First, we show the effects of the metallicity of the environment on their rotation…
To study the variability of the 523 B and Be stars observed in the Magellanic clouds with the VLT-FLAMES, we cross-matched the stars of our sample with the photometric database MACHO, which provides for each star an 8 years lightcurve. We…
Since the early nineties it is accepted that the excitation mechanism of B-type pulsators on the main sequence is due to the opacity peak in the iron-group elements at $T\approx 200,000$ K. The Fe content plays then a major role in the…
Pulsation in beta Cep and SPB stars are driven by the kappa mechanism which depends critically on the metallicity. It has therefore been suggested that beta Cep and SPB stars should be rare in the Magellanic Clouds which have lower…
Slowly Pulsating B and $\beta$ Cephei are $\kappa$ mechanism driven pulsating B stars. That $\kappa$ mechanism works since a peak in the opacity due to a high number of atomic transitions from iron-group elements occurs in the area of $\log…
At low metallicity, B-type stars show lower loss of mass and, therefore, angular momentum so that it is expected that there are more Be stars in the Magellanic Clouds than in the Milky Way. However, till now, searches for Be stars were only…
Until very recently the physical mechanism driving oscillations in $\beta$~Cep and other early type stars has been a mystery. The breakthrough came with the publication of new OPAL and OP opacity data. Model calculations with the new…
We search for effects of metallicity on B and Be stars in the Small and Large Magellanic Clouds (SMC and LMC) and in the Milky Way (MW). We extend our previous analysis of B and Be stars populations in the LMC to the SMC. The rotational…
Thanks to observations at the ESO VLT with the GIRAFFE multifibers spectrograph, we have obtained spectra of 177 and 346 B-type stars in the Large and Small Magellanic Clouds respectively. We have discovered 25 and 90 new Be stars among the…
We present the results of a photometric survey for Be stars in eleven young clusters in the Large Magellanic Cloud and fourteen young clusters in the Small Magellanic Cloud. B stars with hydrogen in emission are identified on the basis of…
The Large and Small Magellanic Clouds are priviledged environments to perform tests of theoretical predictions at low metallicity on rotational velocities and stellar evolution. According to theoretical predictions, the rotational…
We show the vsini distribution of main sequence B stars in sites of various metallicities, in the absolute magnitude range -3.34 < Mv < -2.17. These include Galactic stars in the field measured by Abt et al. (2002), members of the h & chi…
The effects of opacities in driving pulsations and extending the pulsation instability region for B-type stars (SPB and $\beta$ Cep variables) have recently been explored by, e.g., Walczak et al. 2015, 2017, Daszynska-Daszkiewicz et al.…
We present key sample results of a systematic survey of the pulsation properties of models of hot B subdwarfs. We use equilibrium structures taken from detailed evolutionary sequences of solar metallicity (Z = 0.02) supplemented by grids of…
We review the nature of the oscillations of main-sequence and supergiant stars of spectral type B. Seismic tuning of the interior structure parameters of the $\beta $Cep stars has been achieved since three years. The results are based on…