Related papers: Modelling the composition of a young star cluster …
Recent observations of high-redshift galaxies have revealed starburst galaxies with excessive amounts of nitrogen, well above that expected in standard evolutionary models. The Sunburst Arc galaxy, particularly its young and massive star…
Although the present-day Sun rotates too slowly to exhibit centrifugally-supported 'slingshot prominences', at some time during its past it may have formed these clouds of cool gas and ejected them into the interplanetary medium. We…
We use the growing data sets of very-metal-poor stars to study the impact of stellar winds of fast rotating massive stars on the chemical enrichment of the early Galaxy. We use an inhomogeneous chemical evolution model for the Galactic halo…
Abundance patterns of the elements C, N, and O are sensitive probes of stellar nucleosynthesis processes and, in addition, O abundances are an important input for stellar age determinations. Understanding the nature of the observed…
We investigate Wolf-Rayet (WR) stars as a source of feedback contributing to the removal of natal material in the early evolution of massive star clusters. Despite previous work suggesting that massive star clusters clear out their natal…
We present a new implementation of star formation in cosmological simulations, by considering star clusters as a unit of star formation. Cluster particles grow in mass over several million years at the rate determined by local gas…
According to previous spectral analyses of Wolf-Rayet type central stars, late [WC] subtypes show systematically higher carbon-to-helium abundance ratios than early [WC] subtypes. If this were true, it would rule out that these stars form…
Studies of evolved massive stars indicate that they form in a clustered mode. During the earliest evolutionary stages, these regions are embedded within their natal cores. Here, we show high-spatial-resolution interferometric dust continuum…
Context. Oxygen sequence Wolf-Rayet (WO) stars represent a very rare stage in the evolution of massive stars. Their spectra show strong emission lines of helium-burning products, in particular highly ionized carbon and oxygen. The…
Deep, near-infrared JHK-maps were observed for 10 nearby, grand-design, spiral galaxies using HAWK-I/VLT to study the distribution of young stellar clusters in them and thereby determine whether strong spiral perturbations can influence…
Grids of models of massive stars ($M \ge$ 20 $M_\odot$) with rotation are computed for metallicities $Z$ ranging from that of the Small Magellanic Cloud (SMC) to that of the Galactic Centre. The hydrostatic effects of rotation, the…
The rotational evolution of a young stellar population can give informations about the rotation pattern of more evolved clusters. Combined with rotational period values of thousands of young stars and theoretical propositions about the…
Using the latest stellar evolution models, theoretical stellar spectra, and a compilation of observed emission line strengths from Wolf-Rayet (WR) stars, we construct evolutionary synthesis models for young starbursts. We explicitly…
Several observational and theoretical studies suggest that the initial mass function (IMF) slope for massive stars in globular clusters (GCs) depends on the initial cloud density and metallicity, such that the IMF becomes increasingly…
An overview of our current understanding of the formation and evolution of star clusters is given, with main emphasis on high-mass clusters. Clusters form deeply embedded within dense clouds of molecular gas. Left-over gas is cleared within…
We present extensive sets of stellar models for 0.8-9.0Msun in mass and -5 <= [Fe/H] <= -2 and Z = 0 in metallicity. The present work focuses on the evolutionary characteristics of hydrogen mixing into the He-flash convective zones during…
Molecular outflows in the form of wide-angle winds and/or well-collimated jets are associated with young stellar objects of all luminosities. Independent studies have established that the mass outflow rate is proportional to L_bol^0.6 for…
The residual gas within newly formed star clusters is expelled through stellar feedback on timescales ~ 1 Myr. The subsequent expansion of the cluster results in an unbinding of a fraction of stars before the remaining cluster members can…
Strong metallicity-dependent winds dominate the evolution of core He-burning, classical Wolf-Rayet (cWR) stars, which eject both H and He-fusion products such as 14N, 12C, 16O, 19F, 22Ne and 23Na during their evolution. The chemical…
Planet-forming circumstellar disks are a fundamental part of the star formation process. Since stars form in a hierarchical fashion in groups of up to hundreds or thousands, the UV radiation environment that these disks are exposed to can…