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Massive and luminous O-star atmospheres with winds have been studiedprimarily using one-dimensional (1D), spherically symmetric, and stationarymodels. However, observations and theory rather suggest that O-star atmospheresare highly structured, turbulent, and time-dependent. As such, when comparingto observations, present-day 1D modeling tools need to introduce ad-hocquantities such as photospheric macro & microturbulence, wind clumping, etc. Wepresent multi-dimensional, time-dependent, radiation-hydrodynamical (RHD)simulations for O-stars that encapsulate the deeper sub-surface envelope (downto T ~ 450 kK) as well as the supersonic line-driven wind outflow in oneunified approach. Time-dependent, two-dimensional (2D) simulations of O-staratmospheres with winds are performed using a flux-limiting RHD finite volumemodeling technique. Opacities are computed using a hybrid approach combiningtabulated Rosseland means with calculations (based on the Sobolevapproximation) of the enhanced line opacities expected for supersonic flows.When compared to 1D models, the average structures in the 2D simulationsdisplay less envelope expansion, no sharp density-inversions, density andtemperature profiles that are significantly less steep around the photosphere,and a strong anti-correlation between velocity and density in the supersonicwind. To qualitatively match the different density and temperature profilesseen in our multi-D and 1D models, we need to add a modest amount of convectiveenergy transport in the deep sub-surface layers and a large turbulent pressurearound the photosphere to the 1D models.

2D Unified Atmosphere and Wind Simulations of O-stars