Related papers: Observations of Extremely Metal-Poor O Stars: Weak…
Carbon and oxygen are key tracers of the Galactic chemical evolution; in particular, a reported upturn in [C/O] towards decreasing [O/H] in metal-poor halo stars could be a signature of nucleosynthesis by massive Population III stars. We…
Massive stars lose a large fraction of their mass to radiation-driven winds throughout their entire life. These outflows impact both the life and death of these stars and their surroundings. Theoretical mass-loss rates of hot, massive stars…
Recent findings hint that the winds of massive stars with poorer metallicity than the SMC may be stronger than predicted by theory. Besides calling the paradigm of radiation driven winds into question, this result would impact the predicted…
We present a spectroscopic analysis of VLT/X-Shooter observations of six O-type stars in the low-metallicity (Z ~ 1/7 Z\odot) galaxies IC 1613, WLM and NGC 3109. The stellar and wind parameters of these sources allow us, for the first time,…
A small subset of Galactic O-stars possess surface magnetic fields that alter the outflowing stellar wind by magnetically confining it. Key to the magnetic confinement is that it induces rotational modulation of spectral lines over the full…
Mass loss through a stellar wind is an important physical process that steers the evolution of massive stars and controls the properties of their end-of-life products, such as the supernova type and the mass of compact remnants. For an…
Context. Results from the theory of radiatively driven winds are incorporated in stellar evolutionary and population synthesis models, and used in our interpretation of the observations of the deep Universe. Yet, the theory has been…
Spectroscopic observations have shown for decades that the Wolf-Rayet (WR) phenomenon is ubiquitous among stars with different initial masses. Although much effort to understand the winds from massive WR stars has been presented in the…
Fast line-driven stellar winds play an important role in the evolution of planetary nebulae. We provide global hot star wind models of central stars of planetary nebulae. The models predict wind structure including the mass-loss rates,…
Massive stars are "cosmic engines" (cf the title of the IAU Symposium 250). They drive the photometric and chemical evolution of galaxies, inject energy and momentum through stellar winds and supernova explosions, they modify in this way…
The formation and evolution of light elements in the Universe act as important cosmological constraints. It has long been assumed that the oldest stars of the Galaxy display the primordial Li abundance in their outer layers, although…
We present a quantitative study of the stellar and wind properties of massive stars in the compact star forming region SMC-N81. Non-LTE spherically extended atmosphere models including line-blanketing have been computed with the code CMFGEN…
We present synthetic ultraviolet spectra of metal-poor star-forming galaxies which were calculated with the Starburst99 package. A new spectral library was generated from HST observations of O stars in the Large and Small Magellanic Clouds.…
The chemical enrichment of the Universe; the mass spectrum of planetary nebulae, white dwarfs and gravitational wave progenitors; the frequency distribution of Type I and II supernovae; the fate of exoplanets ... a multitude of phenomena…
We report new measurements of carbon and oxygen abundances in 34 F and G dwarf and subgiant stars belonging to the halo population and spanning a range of metallicity from [Fe/H] = -0.7 to -3.2 . The survey is based on observations of four…
The emergence of the disc in our Galaxy and the relation of the thick and thin disc formation and evolution is still a matter of debate. The chemo-dynamical characterization of disc stars is key to resolve this question, in particular at…
We present extensive calculations of the structure and the evolution of low-massstars in the range 0.07-0.8 $\msol$, for metallicities $-2.0\le \mh \le 0.0$. These calculations are based on the most recent description of the microphysics…
Mass-loss rate is one of the most important stellar parameters. We aim to provide mass-loss rates as a function of subdwarf parameters and to apply the formula for individual subdwarfs, to predict the wind terminal velocities, to estimate…
Because of their low gravitational energies dwarf galaxies are greatly exposed to energetical influences by the interstellar medium, like e.g. stellar radiation, winds or explosions, or by their environment. While the metallicity depletion…
We investigate the differential effects of metal cooling and galactic stellar winds on the cosmological formation of individual galaxies with three sets of cosmological, hydrodynamical zoom simulations of 45 halos in the mass range…