We present first results from three-dimensional hydrodynamic simulations of the high redshift formation of dwarf galaxies. The simulations use an Eulerian adaptive mesh refinement technique to follow the non–equilibrium chemistry of hydrogen and helium with cosmological initial conditions drawn from a popular Λ-dominated cold dark matter model. We include the effects of reionization using a uni...

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 in dwarf galaxies can be explained in general by supernova-driven galactic winds, the reason for their low N/O ratios at low O abundance is not yet completel...

This paper argues that star forming environments should be classified into finer divisions than the traditional isolated and clustered modes. Using the observed set of galactic open clusters and theoretical considerations regarding cluster formation, we estimate the fraction of star formation that takes place within clusters. We find that less than ∼ 10% of the stellar population originates fro...

Aims. We investigate the influence of high–energy stellar radiation at close–in orbits on atmospheric mass loss during stellar evolution of a G–type star. Methods. High–energy stellar luminosity varies over a wide range for G field stars. The temporal evolution of the distribution of stellar X–ray luminosity and its influence on the evolution of close–in exoplanets is investigated. X–ray lumino...

We show that the mass fraction of giant molecular cloud (GMC) gas (n 100 cm−3) in dense (n 104 cm−3) star-forming clumps, observable in dense molecular tracers (LHCN/LCO(1–0)), is a sensitive probe of the strength and mechanism(s) of stellar feedback, as well as the star formation efficiencies in the most dense gas. Using high-resolution galaxy-scale simulations with pc-scale resolution and exp...

Context. B[e] supergiants are known to have non-spherical winds, and the existence of disks that are neutral in hydrogen close to their stellar surface has been postulated. A suitable mechanism to produce non-spherical winds seems to be rapid rotation, and at least for three B[e] supergiants in the Magellanic Clouds rotation velocities at a substantial fraction of their critical velocity have b...

The empirically determined universal power-law shape of X-ray luminosity function of high mass X-ray binaries in galaxies is explained by fundamental mass-luminosity and mass-radius relations for massive stars. The unique possibilities offerred by modern X-ray space observatories Chandra and XMM-Newton make it possible to observe point-like X-ray sources in nearby galaxies which allows studies ...

The final mass of a newborn star is set at the epoch when the mass accretion onto the star is terminated. We study the evolution of accreting protostars and the limits of accretion in low metallicity environments. Accretion rates onto protostars are estimated via the temperature evolution of prestellar cores with different metallicities. The derived rates increase with decreasing metallicity, f...