Objective Massive stars, i.e. stars that are up to million times brighter than ordinary stars such as our Sun, play many important roles in astrophysics. They can be considered as (I) Cosmic Engines as they transformed the pristine and dark Universe left after the Big Bang into the modern Universe in which we live today. We use them as (II) Cosmic Probes to study the most distant galaxies and we monitor their eruptions and explosions as (III) Cosmic Transients. As a result, various fields in astrophysics heavily rely on the input of stellar models. Unfortunately, the widely used models are out-dated: they consider massive stars to be single. Recently, large observing campaigns with world-class telescopes provided quantitative showing that the large majority of massive stars will interact with a close binary companion (e.g. Sana & de Mink et. al. Science 2012). This project aims to investigate and quantify how binarity affects the many roles that massive stars played throughout cosmic time. Apart from a few pioneering studies, the exploration of these effects is still in its infancy. Progress has been hampered by (I) the challenging nature of the computations, (II) the many uncertainties in the models and until recently (III) the lack of observational constraints. I propose to overcome these challenges by adopting an unique and innovative approach that combines the strengths of three highly complementary state-of-the art computational tools that will be confronted directly with observational data. I demonstrated the feasibility and high impact of this approach to derive the urgently needed constraints on the impact of binarity on stellar populations in exploratory studies (De Mink et al. 2013, 2014). In this effort I will strongly benefit from my large international network as well as the complementary expertise at the institute in Amsterdam. Fields of science natural sciencesphysical sciencesastronomyobservational astronomygravitational wavesnatural sciencesphysical sciencesnuclear physicsnatural sciencesphysical sciencesastronomyphysical cosmologybig bangnatural sciencesphysical sciencesastronomyastrophysicsblack holes Programme(s) H2020-EU.1.3. - EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions Main Programme H2020-EU.1.3.2. - Nurturing excellence by means of cross-border and cross-sector mobility Topic(s) MSCA-IF-2014-EF - Marie Skłodowska-Curie Individual Fellowships (IF-EF) Call for proposal H2020-MSCA-IF-2014 See other projects for this call Funding Scheme MSCA-IF-EF-RI - RI – Reintegration panel Coordinator UNIVERSITEIT VAN AMSTERDAM Net EU contribution € 165 598,80 Address Spui 21 1012WX Amsterdam Netherlands See on map Region West-Nederland Noord-Holland Groot-Amsterdam Activity type Higher or Secondary Education Establishments Links Contact the organisation Opens in new window Website Opens in new window Participation in EU R&I programmes Opens in new window HORIZON collaboration network Opens in new window Total cost € 165 598,80