Variable and Non-spherical Stellar Winds in Luminous Hot Stars

There is abundant evidence that essentially all luminous hot-star winds contain time-dependent and anisotropic structures. IAU Colloquium 169 was convened to review the observations of variability and asphericity, to discuss the physical processes that might cause such behavior and to look for evolutionary consequences. The topics included OBA stars, Be stars, Wolf-Rayet stars, Be stars, and luminous blue variables (LBVs). The role played by rotation in shaping the stellar wind was a recurrent theme. Photospheric pulsations and/or magnetic fields are particularly appealing mechanisms for triggering the formation of recurrent wind structures.

Rotationally modulated winds of O stars.- Rotationally modulated winds of BA-type supergiants.- Using spectropolarimetry to determine envelope geometry and test variability models for hot star circumstellar envelopes.- Disks of classical be stars.- Evidence for azimuthal asymmetry in be star winds.- Short and medium term variability of emission lines in selected southern Be stars.- Disk winds of B[e] supergiants.- Polarimetric evidence of non-spherical winds.- Wolf-rayet wind models: Photometric and polarimetric variability.- Anisotropic outflows from LBVs and Ofpe/WN9 stars.- Non-isotropic outflows in the infrared: ISO imaging of LBVs.- Radio evidence for non-isotropic outflows from hot stars.- Optical interferometry of non-spherical winds.- Direct observational evidence for magnetic fields in hot stars.- HST WFPCII observations of the inner HR car nebula.- Observing hot stars in all four stokes parameters.- Inverse spectropolarimetric modelling of hot star wind structure and variability.- Physics of radiatively driven winds by high angular resolution observations (HARO).- Wind-compressed disks.- Non-spherical radiation-driven wind models.- Radiation-driven disk winds.- Radiative fluxes and forces in non-spherical winds.- Line-driven ablation by external irradiation.- Extremely luminous atmospheres.- Disks formed by rotation induced bi-stability.- The effects of magnetic fields on the winds from luminous hot stars.- Modeling oblique rotators: Magnetospheres and winds.- X-ray emission from magnetically confined winds.- O-star wind variability in the ultraviolet and optical range.- X-ray evidence for wind instabilities.- X-ray variability of the O star ? Puppis.- On the variable winds of BA supergiants.- UV wind variability in B supergiants and its implications for wind structures.- Variability and evidence of non-spherical stellar winds in A-type supergiants.- Variable winds in early-B hypergiants.- Wind variations of wolf-rayet stars.- Spectral analyses of wolf-rayet stars: The impact of clumping.- The long-term variability of luminous blue variables.- Blitz model for the eruptions of eta carinae.- Short-term variations of LBV’s.- Imaging polarimetry of eta carinae with the hubble space telescope.- Non-spherical outflows in massive binary systems: Circumbinary disks?.- Long-term behaviour of the variable wind of P Cygni.- High-resolution spectroscopy of stellar winds in recently recognized LBV candidates.- Evidence for wind anisotropies from dust formation by wolf-rayet stars.- ISO-SWS spectroscopy of B[e] stars.- The line-driven instability.- Co-rotating interaction regions in 2D hot-star wind models with line-driven instability.- Pulsations in O stars.- Non-radial pulsations of BA supergiants and Be stars.- Theory of pulsational instabilities of hot stars.- Non-radially pulsating hot stars: Non-radial pulsations and Be phenomenon.- Pulsation hydrodynamics of luminous blue variables and pulsation-driven winds.- Linear strange modes in massive stars.- Instabilities in LBVs and WR stars.- The evolution of non-spherical and non-stationary winds of massive stars.- Rotation and anisotropic losses of mass and angular momentum.- Rotation and wolf-rayet star formation.- Dusty LBV nebulae: Tracing the mass loss history of the most massive stars.- Wolf-rayet and LBV nebulae as the result of variable and non-spherical stellar winds.- Ring nebulae abundances: Probes of the evolutionary history of luminous blue variable stars.- The wind momentum — Luminosity relationship of blue supergiants.- Conference summary: The demise of spherical and stationary winds.