New research group to study multiple star systems at MPA

Did you ever wonder that in science fiction stories or series, all the other worlds look remarkably similar to ours? Mainly the protagonists interact with alien civilizations on a planet around another star. Rarely do they depict multiple-star systems – but these are actually fairly common in our Universe. So far, research in multiple systems has mainly focused on binaries, i.e., two stars or compact objects orbiting each other. However, the availability of ever more computing power and the start of gravitational wave astronomy – whose sources include merging multiple systems – have induced Adrian Hamers to start a new Max Planck Research Group at MPA. He will be joined by two postdoctoral fellows in early 2020, and is currently recruiting a PhD student.

The group will develop a new population synthesis code to quickly follow the evolution of a large number of systems on a dedicated computing cluster and to make statistical predictions, which can then be compared to observations. This will yield deeper insight into the origin and evolution of multiple star systems. To study a wide variety of systems, during all stages of stellar evolution, in low and high-density environments, many physical ingredients and a combination of different codes will have to be incorporated into the model to make fast computation possible. The model can then be applied to mergers of compact objects leading to gravitational wave sources and supernovae events, as well as to the evolution of (exo)planets in single and multiple star systems. In addition, the group will develop another code using state-of-the-art techniques to study the evolution of individual systems in greater detail (at the cost of being much more computationally expensive). This detailed code will also help to check and calibrate the fast population synthesis code.

This research might give new answers to the question of how black holes could merge in our Universe in the first place. The progenitor stars that are massive enough to form black holes become very large during their evolution, so a close pair of massive stars would likely merge before they could become black holes. And if the stars evolved separately, i.e., far enough apart, how then did they get closer? The answer could be the interaction with a third object, or even more objects – the dynamics, coupled with stellar and binary evolution, can get very complicated in this case.

And that is what fascinates the theoretical and computational astrophysicist Adrian Hamers: the dynamics and interactions of celestial bodies. Already while studying physics and astronomy at Utrecht University, he worked on binary and triple systems, directly applying theoretical physics and astrophysics to the real Universe. He obtained his PhD supervised by Simon Portegies Zwart at the Computational Astrophysics group of Leiden Observatory, Leiden University, in 2016 with a thesis on “Hierarchical Systems” and then continued as a postdoctoral fellow at the Institute for Advanced Study in Princeton, NJ, USA. In September 2019, he started his new Max Planck Research Group on Multiple Star Evolution at MPA.

Much of Adrian’s inspiration to pursue astrophysics comes from science fiction such as the Star Trek and Stargate series. In his youth, Adrian already spent quite a bit of time with his (German) mother’s family near Hanover, but this is his first time coming to Germany in an academic context. He enjoys the Bavarian nature, the spacious environment (compared to his home country, the Netherlands), and is already planning skiing holiday with his family in the Alps. He is an avid pianist, and has a particular interest in historical keyboard instruments such as the harpsichord and fortepiano.