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We discuss properties and examples of r-mode (large scale Rossby wave) oscillations in rotating stars. Motions are nearly toroidal but affected weakly by buoyancy. R modes seem to be excited mechanically in most cases, and ubiquitous in…
The identification of individual stars in crowded environments using photometric information alone is confounded by source confusion. However, with the addition of spectroscopic information it is possible to distinguish between blends and…
We present a preliminary analysis of time series photometry on the pulsating subdwarf B star PG1336-018 acquired as part of two Whole Earth Telescope runs. PG1336-018 is a multi-mode pulsator with at least 15 periods centered around 175…
We present updated measurements for the position angle and separation of the double-star WDS 09168-3407 B 1118, incorporating data from our observation, Gaia Early Data Release 3 mission, and historical records. Our findings indicate a…
We started a program to search for companions around hybrid $\delta$ Sct/$\gamma$ Dor stars with the frequency modulation method using Kepler data. Our best candidate was KIC 5709664, where we could identify Fourier peaks with sidelobes,…
We report on low resolution (R~3000) spectropolarimetry of the A0 supergiant star HD 92207. This star is well-known for significant spectral variability. The source was observed on seven different nights spanning approximately 3 months in…
We investigate the multiplicity properties of 408 B-type stars observed in the 30 Doradus region of the Large Magellanic Cloud with multi-epoch spectroscopy from the VLT-FLAMES Tarantula Survey (VFTS). We use a cross-correlation method to…
A method for the asteroseismic analysis of beta Cephei stars is presented and applied to the star nu Eridani. The method is based on the analysis of rotational splittings, and their asymmetries using differentially-rotating asteroseismic…
We report on extended photometry of two pulsating sdB stars in close binaries. For both cases, we use rotational splitting of the pulsation frequencies to show that the sdB component rotates much too slowly to be in synchronous rotation. We…
We present the analysis of simultaneous multicolour $uvyI_{\rm C}$ photometry and low-resolution spectroscopy for the rapidly rotating $\beta$ Cephei star SY Equ. From the photometric time series, we confirm the dominant pulsation…
A method for obtaining asteroseismological information of a Gamma Doradus oscillating star showing at least three pulsation frequencies is presented. This method is based on a first-order asymptotic g-mode expression, in agreement with the…
Context. Stars in transition phases, like those showing the B[e] phenomenon and luminous blue variables (LBVs), undergo strong, often irregular mass ejection events. The prediction of these phases in stellar evolution models is therefore…
We combine photometric and spectroscopic data on twelve modes excited in FG Vir to determine their spherical harmonic degrees, $\ell$, and to obtain constraints on the star model. The effective temperature consistent with the mean colours…
We present the detection and analysis of line index variations in the pulsating sdB star PG 1605+072. We have found a strong dependence of line index amplitude on Balmer line order, with high-order Balmer line amplitudes up to 10 times…
To optimise the science results of the asteroseismic part of the CoRoT satellite mission a complementary simultaneous ground-based observational campaign is organised for selected CoRoT targets. The observations include both high-resolution…
In this paper we describe a Bayesian statistical method designed to infer the magnetic properties of stars observed using high-resolution circular spectropolarimetry in the context of large surveys. This approach is well suited for…
The overtone and multi-mode RR Lyrae stars in the globular cluster M3 are studied using a 200-d long, $B,V$ and $I_{\mathrm C}$ time-series photometry obtained in 2012. 70\% of the 52 overtone variables observed show some kind of…
Asteroseismology of F-type stars has been hindered by an ambiguity in identification of their oscillation modes. The regular mode pattern that makes this task trivial in cooler stars is masked by increased linewidths. The absolute mode…
We present a survey of nonradial mode properties in evolutionary sequences of RR Lyrae star models. Attention is focused on the modes that may be driven by the opacity mechanism and on those that may be excited as a consequence of the 1:1…
The F8Ia supergiant V810 Centauri is part of a long-term high-precision photometric monitoring program on long period variables started twenty years ago. Time series analysis of this unique set of 500 data points, spanning almost fifteen…