We present the preliminary result of our spectroscopic observations covering a period over more than ten years, from 1999 up to 2010. We analyze line profile variations of several lines before the shell phase and during the shell phase. The measured radial velocity, equivalent width and line intensity variations are presented.

For early type magnetic stars slow, at most moderate rotational velocities have been considered an observational fact. The detection of a multi-kilogauss magnetic field in the B2Vpn star with P ≈ 0.52 d and v sin i ≈ 300 km/s has brought down this narrative. We have obtained more than 100 high-resolution, high-S/N echelle spectra in 2009. These spectra provide the most detailed description of the variability of any He-strong star to date. The circumstellar environment is dominated by a rotationally locked magnetosphere out to several stellar radii, causing hydrogen emission. The photosphere is characterized by surface chemical abundance inhomogeneities, with much stronger amplitudes, at least for helium, than slower rotating stars like σ Ori E. The highly complex rotational line profile modulations of metal lines are probably a consequence the equatorial gravity darkening of HR 7355, and thus may offer an independent measurement of the von Zeipel parameter β.

First we investigate the spectral and photometric properties (colours, magnitudes) of a sample of faint Be stars observed in the first exoplanet fields of CoRoT (IR1, LRA1 and LRC1). We determine the fundamental parameters by fitting ESO-FLAMES/GIRAFFE spectra with synthetic models taking account for non-LTE effects. After that we correct these parameters from fast rotation effects. We also study the location of each star in the (logL vs logT) HR diagram. Second we start to analyse the CoRoT light curves to investigate further the possible correlation between the pulsating properties and the fundamental parameters of the stars.

Identifying seven activities and activity-carrying properties and nine classes of Active OB Stars, the OB Star Activity Matrix is constructed to map the parameter space. On its basis, the occurrence and appearance of the main activities are described as a function of stellar class. Attention is also paid to selected combinations of activities with classes of Active OB Stars. Current issues are identified and suggestions are developed for future work and strategies.

We present interferometric observations of the Be star ζ Tau obtained using the MIRC beam combiner at the CHARA Array during four epochs in 2007–2009. Fitting a geometric model to the data reveals a nearly edge-on disk with a FWHM of ~1.8 milli-arcsec in the H-band. The non-zero closure phases indicate an asymmetry in the brightness distribution. Interestingly, when combining our results with previously published interferometric observations of ζ Tau, we find a correlation between the position angle of the disk and the spectroscopic V/R ratio, suggesting that the tilt of the disk might be precessing. This work is part of a multi-year monitoring campaign to investigate the development and outward motion of asymmetric structures in the disks of Be stars.

GG Car is a peculiar B type star with emission lines classified as a B[e] supergiant star. In this work we present a spectral analysis of this system based on spectra obtained at Casleo. We fit the spectral energy distribution adopting a model for the gas and dust circumstellar components and thus we obtain the physical parameters of the star and its environment.

Massive hot stars are strong sources of X-ray emission originating in their winds. Although hydrodynamical wind simulations that are able to predict this X-ray emission are available, the inclusion of X-rays in stationary wind models is usually based on crude approximations. To improve this, we use results from time-dependent hydrodynamical simulations of the line-driven wind instability to derive an analytical approximation of X-ray emission in the stellar wind. We use this approximation in our non-LTE wind models and find that an improved inclusion of X-rays leads to a better agreement between model ionization fractions and those derived from observations. Furthermore, the slope of the Lx-L relation is in better agreement with observations, albeit the X-ray luminosity is underestimated by a factor of three. We propose that a possible solution for this discrepancy is connected with the wind porosity.

During the LBV phase—a short transitional phase of only the very massive stars—strong stellar winds sometimes accompanied by eruptions form small circumstellar LBV nebulae around a substantial number of LBV stars. Analyzing the morphology and and kinematics of the LBV nebulae even weakly bipolar components can be detected, leading to the conclusion that about 50% have—to some degree—a bipolar structure. A global overview of our current observational knowledge of LBV nebulae is summarized, including their morphology, sizes and kinematic parameters.

We report the first dynamic mass for an O-type supergiant, the interferometrically resolved SB2 system ζ Ori A (O9.5Ib+B0/1). The separation of the system excludes any previous mass-transfer, ensuring that the derived masses can be compared to single star evolutionary tracks.

First results of near-IR adaptive optics (AO)-assisted imaging, interferometry, and spectroscopy of this Luminous Blue Variable (LBV) are presented. They suggest that the Pistol Star is at least double. If the association is physical, it would reinforce questions concerning the importance of multiplicity for the formation and evolution of extremely massive stars.

We report on the abundances of helium, carbon, nitrogen and oxygen in a larger sample of Galactic massive stars of ~7-20 M⊙ near the main sequence, composed of apparently normal objects, pulsators of β-Cephei- and SPB-type, and magnetic stars. High-quality spectra are homogeneously analysed using sophisticated non-LTE line-formation and comprehensive analysis strategies. All the stars follow a previously established tight trend in the N/C-N/O ratio and show normal helium abundances, tracing the nuclear path of the CNO-cycles quantitatively. A correlation of the strength of the mixing signature with the presence of magnetic fields is found. In conjunction with low rotation velocities this implies that magnetic breaking is highly efficient for the spin-down of some massive stars. We suggest several objects for follow-up spectropolarimetry, as the mixing signature indicates a possible magnetic nature of these stars.

The presence of magnetic fields at the surfaces of many massive stars has been suspected for decades, to explain the observed properties and activity of OB stars. However, very few genuine high-mass stars had been identified as magnetic before the advent of a new generation of powerful spectropolarimeters that has resulted in a rapid burst of precise information about the magnetic properties of massive stars. During this talk, I will briefly review modern methods used to diagnose magnetic fields of higher-mass stars, and summarize our current understanding of the magnetic properties of OB stars.

The coupling between the convective region in the envelope and rotation can produce a surface latitudinal differential rotation that may induce changes of the stellar geometry and on the spectral line profiles that it may be scrutinized spectroscopically and by interferometry.

B[e] stars are among the most peculiar objects in the sky. This spectral type, characterised by allowed and forbidden emission lines, and a large infrared excess, does not represent an homogenous class of objects, but instead, a mix of stellar bodies seen in all evolutionary status. Among them, one can find Herbig stars, planetary nebulae central stars, interacting binaries, supermassive stars, and even “unclassified” B[e] stars: systems sharing properties of several of the above. Interferometry, by resolving the innermost regions of these stellar systems, enables us to reveal the true nature of these peculiar stars among the peculiar B[e] stars.

Double mode pulsations of the B4 component in the system of CI Cam were detected. The photometric 19.4 day orbital period of CI Cam was confirmed with the plates of the Sonneberg collection for a long period of time before the unique 1998 outburst. The amplitude of the periodic component of 0.08 mag before the outburst was larger than that of 0.03 mag after the outburst.

This review describes the observational evidence for structure in the winds of O-type stars due to large-scale perturbations and small-scale inhomogeneities. Despite considerable progress, a comprehensive theoretical framework that explains the origin. properties, and coexistence of wind structure on different spatial scales has yet to be constructed and incorporated into model atmosphere analyses. Consequently, it is not yet possible to assess the effect of non-stationary structures on different wind diagnostics in a rigorous way, with the result that accurate empirical determinations of mass-loss rates remain elusive.

We discuss the recent detection of a strong, organized magnetic field in the bright, broad-line B2V star, HD 142184, using the ESPaDOnS spectropolarimeter on the CFHT as part of the Magnetism in Massive Stars (MiMeS) survey. We find a rotational period of 0.50833 days, making it the fastest-rotating, non-degenerate magnetic star ever detected. Like the previous rapid-rotation record holder HR 7355 (also discovered by MiMeS: Oksala et al. 2010, Rivinius et al. 2010), this star shows emission line variability that is diagnostic of a structured magnetosphere.

The statistical properties of magnetic fields and magnetic fluxes of OB stars were investigated. The mean magnetic fluxes of massive OB stars appear to be 3 order larger than those for neutron stars.

We discuss the origin of the hard X-rays in γ Cas and its analogs. Of great importance are their temporal correlations with optical/UV signatures, suggesting an origin near the Be star.

X-rays give direct evidence of instabilities, time-variable structure, and shock heating in the winds of O stars. The observed broad X-ray emission lines provide information about the kinematics of shock-heated wind plasma, enabling us to test wind-shock models. And their shapes provide information about wind absorption, and thus about the wind mass-loss rates. Mass-loss rates determined from X-ray line profiles are not sensitive to density-squared clumping effects, and indicate mass-loss rate reductions of factors of 3 to 6 over traditional diagnostics that suffer from density-squared effects. Broad-band X-ray spectral energy distributions also provide mass-loss rate information via soft X-ray absorption signatures. In some cases, the degree of wind absorption is so high, that the hardening of the X-ray SED can be quite significant. We discuss these results as applied to the early O stars ζ Pup (O4 If), 9 Sgr (O4 V((f))), and HD 93129A (O2 If*).