Related papers: Wolf-Rayet Populations at High Metallicity

Stripped-envelope stars can be observed as Wolf-Rayet (WR) stars, or as less luminous hydrogen-poor stars with low mass loss rates and transparent winds. Both types are potential progenitors of Type I core-collapse supernovae (SNe). We use…

Recent surveys of the Magellanic Clouds have revealed a subtype of Wolf-Rayet (WR) star with peculiar properties. WN3/O3 spectra exhibit both WR-like emission and O3 V-like absorption - but at lower luminosity than O3 V or WN stars. We…

The entire evolution of the Milky Way, including its mass-assembly and star-formation history, is imprinted onto the chemo-dynamical distribution function of its member stars, f(x, v, [X/H]), in the multi-dimensional phase space spanned by…

We present the first determination of the radial velocities and metallicities of 78 red giant stars in the isolated dwarf irregular galaxy WLM. Observations of the calcium II triplet in these stars were made with FORS2 at the VLT-UT2 in two…

(Abridged) We performed a multiwavelength analysis of a sample of starburst galaxies that show the presence of a substantial population of very young massive (WR) stars. Here we present the global analysis of the derived photometric and…

For the past three years we have been conducting a survey for WR stars in the Large and Small Magellanic Clouds (LMC, SMC). Our previous work has resulted in the discovery of a new type of WR star in the LMC, which we are calling WN3/O3.…

After a brief review of the observational evidences indicating how the populations of Be stars, red/blue supergiants, Wolf-Rayet stars vary as a function of metallicity, we discuss the implications of these observed trend for our…

We calculated pre-supernova evolution models of single rotating massive stars. These models reproduce observations during the early stages of the evolution very well, in particular Wolf--Rayet (WR) populations and ratio between type II and…

We present a study of the gaseous and stellar emission in I Zw18, the most metal-poor star-forming galaxy known. Archival HST WFPC2 and FOS data have been used to analyze the spatial distribution of [OIII], Halpha, and HeII 4686. The latter…

We present recent results for galactic WNL stars, obtained with the new Potsdam Wolf-Rayet (PoWR) hydrodynamic model atmospheres. Based on a combination of stellar wind modeling and spectral analysis we identify the galactic WNL subtypes as…

Wolf-Rayet (WR) stars in the Magellanic Clouds (MCs) are ideal for studying the production of X-ray emission by their strong fast stellar winds. We have started a systematic survey for X-ray emission from WR stars in the MCs using archival…

Today, we have a sufficiently complete picture of what the Wolf--Rayet (WR) stars are. Predictions of stellar evolution theory are in a good agreement with their parameters, estimated from observational data using stellar atmospheres codes;…

Context: Recent gamma-ray observations of young star clusters revealed that stellar wind termination shocks accelerate particles, with the energy reservoir provided by the mechanical power of massive-star winds. Aims: Our goal is to…

Evolved Wolf-Rayet stars form a key aspect of massive star evolution, and their strong outflows determine their final fates. In this study, we calculate grids of stellar models for a wide range of initial masses at five metallicities…

We present new yields of 26Al from Wolf--Rayet stellar winds based on rotating stellar models which account well for numerous observed properties of massive stars. We study the impacts on the yields of a change of initial mass, metallicity…

The aim of this paper is to look at the evolution of massive stars in order to determine whether or not the progenitor of V838 Mon may be a massive star. In the first part of this paper, the evolution of massive stars around solar…

We review the properties of massive star evolution in different environments, where the major environmental factor is metallicity. Comparisons between evolutionary models and observations of massive OB, WR stars and related objects are…

Wolf-Rayet stars are advanced evolutionary stages of massive stars. Despite their large mass-loss rates and high wind velocities, none of them display a bow shock, although a fraction of them are classified as runaway. Our 2.5-D numerical…

This paper discusses our ongoing efforts to characterize dust-enshrouded Wolf-Rayet (WR) stars in the radio and infrared. We have used the Very Large Array to measure the broadband radio spectrum of WR stars in suspected binary systems and…

We present a newly observed relation between galaxy mass and radial metallicity gradients of early-type galaxies. Our sample of 51 early-type galaxies encompasses a comprehensive mass range from dwarf to brightest cluster galaxies. The…