Stellar evolution, GRB and their hosts

GRB hosts through cosmic time

We present data and initial results from VLT/X-Shooter emission-line spectroscopy of 96 galaxies selected by long γ-ray bursts (GRBs) at 0.1 < z < 3.6, the largest sample of GRB host spectra available to date. Most of our GRBs were detected by Swift and 76% are at 0.5 < z < 2.5 with a median zmed ∼ 1.6. Based on Balmer and/or forbidden lines of oxygen, nitrogen, and neon, we measure systemic re...

Stellar activity in exoplanet hosts

Most of the efforts on the search and characterization of Earth-like exoplanets are currently focused on low mass stars. These represent the vast majority of the population in our galaxy (about 75% of the stars have a lower mass than the Sun) and their interest lies in the fact that the photometric and spectroscopic signal of orbiting Earth-like planets is higher due to lower star-planet size a...

GRB Progenitors and their environment

The detection of supernova features in the late spectra of several gamma-ray burst afterglows has shown that at least a fraction of long-duration gamma-ray bursts are associated to the final evolutionary stages of massive stars. Such direct observations are impossible for bursts located at redshift beyond z ∼ 0.5 and different methods must be used to understand the nature and properties of thei...

Stellar Structure and Evolution

S ep 2 00 7 The population of GRB hosts

The properties of their hosts provide important clues to the progenitors of different classes of gamma-ray bursts (GRBs). The hosts themselves also constitute a sample of high-redshift star-forming galaxies which, unlike most other methods, is not selected on the luminosities of the galaxies themselves. We discuss what we have learnt from and about GRB host galaxies to date.