The Astrophysics of Stellar Clusters
Stellar clusters are widespread. Globular clusters contain some of the
oldest stars, whilst the youngest stars are found in OB associations
or in other clusters associated with recent star formation.
Such crowded places are hostile environments: a large fraction
of stars will collide or undergo close encounters. Wide binaries
are likely to be broken up, whilst tighter ones will suffer major
pertubations and possibly collisions from passing stars.
A major part of our work is the study of such encounters
using hydrodynamical computer simulations and using the results of such
work to understand how collisions and close encounters
will affect the evolution of stellar
clusters and produce the myriad of stellar exotica seen such as
X-ray binaries, millisecond pulsars, and gamma-ray burst
progenitors.
The cluster of stars at the centre of a galaxy may provide the
material to form a massive black hole and fuel it as a quasar.
Encounters in young clusters will affect planetary systems.
Systems resembling our own solar system may be perturbed
by fly-by encounters or a stellar binary companion, producing
systems more similar to the observed exoplanet systems where
jupiter-mass planets are on tight, eccentric orbits.
Our research can be summarised by three key questions:
- How unusual is our solar system?
- How do black holes form and grow?
- What powers gamma-ray bursts and supernovae?
Our current work is addressing the following questions:
- Can planetary systems survive in stellar clusters?
- How vulnerable are planetary systems like our own solar
system to strong planet-planet scattering due to stellar fly-bys?
- What part do stellar collisions play in the
formation and subsequent growth of massive black holes
in galactic nuclei?
- What happens to the primordial population of binaries as a
cluster evolves?
- How frequently are compact binaries produced in stellar clusters?
- What processes are important in the early evolution of
a young cluster?
- Can we explain the observed locations of short gamma-ray
bursts with respect to their host galaxies?
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