The Massive Star group at API works on a variety of topics relevant for the formation and evolution of massive stars, the majority of which live their lives in close binary systems. In this project, you will be establishing a better understanding of interactions in binary systems, and the impact such interactions have on the further evolution, final fate and feedback of massive stars.

In this context, you will develop new theoretical predictions, both using detailed (MESA) and rapid (e.g., SeBa) stellar-evolution predictions for different physics assumptions, with a particular focus on the spin-up of the accretor star. For this, you will take into account our most recent findings about binary interactions, and develop a new framework to identify counterparts to OBe stars, that is rapidly rotating O- and B-type stars, in the predictions.

The new predictions for entire populations of massive stars will be tailored to modern observations of massive stars, in particular OBe stars in our Milky Way as well as in the ongoing BLOeM survey (Shenar et al. 2024, A&A 690, 289). You will directly compare predictions such as the relative number of different types of companions to OBe stars, their period and eccentricity distributions to the observational findings of those objects derived in our group.

Tasks and responsibilities:

• You will compute new evolutionary predictions for massive binary systems, with a particular focus on OBe stars, and compare their predicted properties to modern observations, for example in the context of the BLOeM survey.
• You will collaborate with other faculty members, postdocs, and students in the Massive star research group as well as international collaborators (in particular as part of the BLOeM collaboration).
• You will have the opportunity to co-advise research projects of PhD, MSc and BSc students as an active member of the Massive Star research group.
• You will contribute to creating an open, safe and inclusive working environment.

• A PhD in astronomy (or equivalent).
• A strong background in stellar astrophysics, especially in stellar-evolution modeling and population synthesis calculations.
• A     committed     researcher,     demonstrated     by     previous     research        experiences, publications and presentations at international conferences.
• The ability and willingness to collaborate and work in a team.
• Excellent communication and writing skills in English.

We offer a temporary employment contract for 38 hours per week for a period of 12 months, and the possibility to be extended for another 12 months upon satisfactory performance. The preferred starting date is flexible, but the latest in Autumn 2026. The gross monthly salary, based on 38 hours per week and dependent on relevant experience, ranges between €3,546 to €5,538 (scale 10). This does not include 8% holiday allowance and 8.3% year-end allowance. The UFO profile Researcher 4 is applicable. The Collective Labour Agreement of Universities of the Netherlands is applicable.

Besides the salary and a vibrant and stimulating environment at Science Park we offer you multiple fringe benefits:

• 232 holiday hours per year (based on fulltime) and extra holidays between Christmas and 1 January;
• multiple courses to follow from our Teaching and Learning Centre;
• multiple courses on topics such as leadership for academic staff;
• multiple courses on topics such as time management, handling stress and an online learning platform with200+ different courses;
• 7 weeks birth leave (partner leave) with 100% salary;
• partly paid parental leave;
• the possibility to set up a workplace at home;
• a pension at ABP for which UvA pays two third part of the contribution;
• the possibility to follow courses to learn Dutch;