Richard de Grijs (何锐思)

Richard's research has evolved from studies of galactic structure to stellar and star cluster population synthesis (well, anything related to star clusters near and far, in fact), although he has placed more recent emphasis on aspects of the astronomical distance scale. He published the first independent evidence that galaxy interactions lead to enhanced star cluster formation and showed that the initial cluster mass function in the prototype "starburst" galaxy M82 may not be a power-law function of mass. This has far-reaching consequences for our ideas of how galaxies evolve. He used the cluster age and mass distributions in the nearby Magellanic Clouds to disprove the notion that 90% of the cluster population is destroyed per decade of logarithmic age (up to 1 Gyr). The major implication is that we have to re-assess our theories of how cluster populations evolve. He has also shown convincingly that "primordial" mass segregation (requiring stars of different masses to form in areas of different densities, hence suggesting a position-dependent stellar initial mass function) may not be required if one adopts realistic initial conditions for numerical simulations of cluster evolution. He obtained the first quantitative evidence for a high fraction (~55%) of "primordial" binary systems in Magellanic Cloud clusters, where his team also showed that dynamical disruption of "soft" binary systems may proceed on very short timescales. Richard's research fundamentally aims at exploring two outstanding key questions: (i) How is star formation triggered and how does it proceed, and (ii) How do the star-formation mode, efficiency and pressure of the interstellar medium lead to the resulting stellar initial mass function and, in particular, what is the role of the massive stars compared to that of their lower-mass counterparts?