Laurent Drissen

A RING NEBULA SURROUNDING EVOLVED MASSIVE STARS IN THE POST-STARBURST GALAXY NGC 1569

Broad stellar emission lines have been detected in the optical spectrum of a small cluster in the post-starburst galaxy NGC 1569. These lines, He I 5876, H-alpha, and He I 6678, have a full width at half maximum of 600 km s-1, and are attributed to a late-type WN star. the cluster, located in the outskirts of the galaxy, is surrounded by a large (Radius = 30 pc) ring nebula. This detection of a Wolf-Rayet star is a direct evidence of recent (≤ 5 Myrs) massive (Mi ≥ 40 solar mass) star formation in NGC 1569.

The Wolf-Rayet and O Star Content of Violent Starbursts

New population synthesis models for starburst regions have been computed, with an emphasis on the W-R population and the output of ionizing photons.

Injection of Mass and Energy into the ISM by Massive Stars

A large set of radiatively driven wind models for massive stars has been computed. We followed the stars from the ZAMS until they reach T eff =15,000 K. The metallicity range is 0.1Z⊙ ≤ Z ≤ 3Z⊙.