Related papers: Inferring hot-star-wind acceleration from Line Pro…
The emission line spectra of WR stars are often formed completely in the optically thick stellar wind. Hence, any assumption on the wind velocity law in a spectral analysis has a profound impact on the determination of the stellar…
$Aims.$ We present a database of 43,340 atmospheric models ($\sim$80,000 models at the conclusion of the project) for stars with stellar masses between 9 and 120 $M_{\odot}$, covering the region of the OB main-sequence and Wolf-Rayet (W-R)…
We analyze recent 2D simulations of the nonlinear evolution of the line-deshadowing instability (LDI) in hot-star winds, to quantify how the associated highly clumped density structure can lead to a "turbulent porosity" reduction in…
High spectral resolution and long exposure times are providing unprecedented levels of data quality of massive stars at X-ray wavelengths. A key diagnostic of the X-ray emitting plasma are the fir lines for He-like triplets. In particular,…
Line ratios in "fir" triplets of helium-like ions have proven to be a powerful diagnostic of conditions in X-ray emitting gas surrounding massive stars. Recent observations indicate that these ratios can be variable with time. The possible…
The winds of massive stars have an impact on stellar evolution and on the surrounding medium. The maximum speed reached by these outflows, the terminal wind speed, is a global wind parameter and an essential input for models of stellar…
We constrain wind parameters of a sample of 18 O-type stars in the LMC, through analysis with stellar atmosphere and wind models including the effects of optically thick clumping. This allows us to determine the most accurate spectroscopic…
Observations of nearby molecular clouds detect "shells", which are likely caused by winds from young main sequence stars. However, the progenitors of these observed features are not well characterized and the mass-loss rates inferred from…
We discuss the development of the new radiative transfer code Wind3D. It solves the non-LTE radiative transport problem in moving stellar atmosphere models in three geometric dimensions. The code accepts arbitrary 3D velocity fields in…
Radiation-driven winds of massive stars can be described within the modified CAK theory, which parametrises the radiation force through three key quantities: $\alpha$, $\delta$, and $k$. Different combinations of these parameters, together…
Mass loss is a key process in the evolution of massive stars, and must be understood quantitatively to be successfully included in broader astrophysical applications. In this review, we discuss various aspects of radiation driven mass loss,…
Wind models of very massive stars with metallicities in a range from 1E-4 to 1.0 solar are calculated using a new treatment of radiation driven winds with depth dependent radiative force multipliers and a comprehensive list of more than two…
Accurate mass-loss rates and terminal velocities from massive stars winds are essential to obtain synthetic spectra from radiative transfer calculations and to determine the evolutionary path of massive stars. From a theoretical point of…
We report on resonance line profiles predicted by radiation driven disk wind models which extend radially one order of magnitude farther out than our previous models. Our main result is that the inclusion of a disk wind at larger radii…
Wolf-Rayet (WR) stars have a severe impact on their environments owing to their strong ionizing radiation fields and powerful stellar winds. Since these winds are considered to be driven by radiation pressure, it is theoretically expected…
We review recent developments regarding radiation driven mass loss from OB-stars. We first summarize the fundamental theoretical predictions, and then compare these to observational results (including the VLT-FLAMES survey of massive…
Stellar evolution models of massive stars are very sensitive to the adopted mass-loss scheme. The magnitude and evolution of mass-loss rates significantly affect the main sequence evolution, and the properties of post-main sequence objects,…
We analyse $\textit{XMM-Newton}$ RGS spectra of Wolf-Rayet (WR) 140, an archetype long-period eccentric WR+O colliding wind binary. We evaluate the spectra of O and Fe emission lines and find that the plasmas emitting these lines have the…
We present the first non-LTE atmosphere models for WR stars that incorporate a self-consistent solution of the hydrodynamic equations. The models account for iron-group line-blanketing and clumping, and compute the hydrodynamic structure of…
This thesis discusses the influence of magnetic fields on the instability of line-driven winds in O-stars and Wolf-Rayet stars. This combination is an important concept to understand the strong, observed winds from Wolf-Rayet stars. In the…