Activities in 1992-1993

From the Report for Academic Year 1992-1993
of the Institute for Advanced Study

PIET HUT's research has focused on the study of dense stellar systems, with applications to globular star clusters and galactic nuclei. He has taken part in the design of large-scale simulations in collisional stellar dynamics, to be performed on the 1 Tflops special-purpose computer under development in the astronomy department at Tokyo University. As part of this effort, new tree-based algorithms for the treatment of close encounters and physical collisions were developed in collaboration with Jun Makino from Tokyo University, and Steve McMillan from Drexel University.

Other studies of globular clusters included a series of Fokker-Planck simulations of post-collapse evolution, in which a detailed investigation was made of the properties of gravothermal oscillations, in collaboration with Joseph Breeden and Haldan Cohn of Indiana University. A theoretical study of the formation and dynamical evolution of stellar-mass black hole remnants in globular clusters was carried out in collaboration with Shri Kulkarni from CalTech and Steve McMillan. This work resulted in potentially interesting observational consequences, by predicting a significant formation rate of black hole containing X-ray binaries.

In response to the recent discovery of a significant population of primordial binaries in globular clusters, Prof. Hut has made a study of binary-binary scattering experiments, partly numerically and partly through analytical calculations, in collaboration with Douglas Heggie from the University of Edinburgh. In addition, together with Steve McMillan, he continued a series of N-body simulations of tidally limited star clusters in which the influence of various populations of primordial binaries was investigated. With Jun Makino and Lars Hernquist, from the University of California at Santa Cruz, he completed a comparative study of the error propagation of various hardware and software limitations on collisional stellar dynamics calculations.

Prof. Hut also took part in a seminar on Science Studies, organized by Prof. Geertz in the School of Social Science.