A large percentage of massive stars are born as part of binary or multiple systems. This statement, which has been defended by some authors during the last 3 decades -and has important consequences on the evolution, final fate and chemo-dynamical feedback of massive stars- has been recently confirmed by intensive spectroscopic, interferometric, and

Rotation is one of the important parameters affecting the evolution and final fate of massive stars. Still the origin of fast- rotating stars in the massive OB domain remains unclear. Although the high spin rates detected in about 20-30% of these stars could just be an imprint of the star formation process, alternative scenarios -supported by the

After almost 12 years gathering data with the 2.56-m Nordic Optical Telescope and the 1.2-m Mercator telescope, the IACOB project has broken the record of compiling high quality, multi-epoch, optical spectra for more than 1000 Northern Galactic O- and B-type stars. To celebrate this important milestone, in this contribution to the first virtual

The long-standing difference in chemical abundances determined from optical recombination lines and collisionally excited lines raises questions about our understanding of atomic physics, as well as the assumptions made when determining physical conditions and chemical abundances in astrophysical nebulae. Here, we study the recombination

We show that quasar microlensing magnification statistics induced by a population of point microlenses distributed according to a mass-spectrum can be very well approximated by that of a single-mass, "monochromatic", population. When the spatial resolution (physically defined by the source size) is small as compared with the Einstein radius, the

By using deep observations of clusters of galaxies, it has been recently found that the projected stellar mass density closely follows the projected total (dark and baryonic) mass density. In this work, we aim to test these observations using the Cluster-EAGLE simulations. We find that the shape of the stellar mass distribution follows that of the