Theoretical Astrophysics in Lund
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
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:
Our current work is addressing the following questions:
- How common are planetary systems which contain habitable worlds?
- How do black holes form, grow and interact with their surroundings?
- What powers the most-energetic explosions in the universe?
- How do rocky planets form in dusty disks?
- How and when do gas-giant planets form?
- Can planetary systems survive in stellar clusters?
- Which planetary systems suffer dynamical instability and what
happens to them?
- What part do nuclear stellar clusters play in the
formation and subsequent growth of massive black holes
in galactic nuclei?
- How frequently are compact binaries produced in stellar clusters?
- What happens to stars and planets in young, gas-rich stellar clusters?
- What are the progenitors of the calcium-rich transients seen
with PTF and how do they relate to gamma-ray bursts?