Seminar 30th October 2014 2 p.m. 177/2011
Sailing the turbulent seas around massive stars
Prof Malcolm Coe
University of Southampton
- Categories
- NGCM
- Submitter
- Susanne Ufermann Fangohr
SPH simulations showing a neutron star (the small point-like object) orbiting and interacting with a massive B-type star surrounded by a circumstellar disk.
Summary
As part of an intensive campaign over the last few years, an exceptionally large population of X-ray emitting binaries has been found to exist in the Small Magellanic Cloud (SMC). Long-term X-ray lightcurves, coupled with optical photometric lightcurves and spectroscopic monitoring with the SALT telescope, provide valuable insights into the size and behaviour of the circumstellar disc in these binaries. Furthermore, more than a dozen of these systems show optical outbursts or binary modulation linked to X-ray phenomena. Linking X-ray observations to the physics of the binary system requires understanding the interaction of complex hydrodynamic and radiative processes within a system depending on a large number of parameters.
The goal of this project will be to improve our understanding of these binary systems and the physics of accretion by modelling the interaction between and evolution of the circumstellar disc and the transiting neutron star. We will use the multiwavelength observations to constrain the parameter space of the modelling and add more realism to the physics of the simulations. For example, we can use the rate of change of the neutron star spin period as an indicator of angular momentum transfer, and hence set limits on the mass-transfer rate. The optical modulation can be used to set limits on the modulation of the circumstellar disc by the gravitational field of the passing neutron star. In order to understand the observations, Smoothed Particle Hydrodynamics (SPH) simulations are used to model these systems.
Bio
Malcolm Coe is a professor of astronomy with over 200 publications in the field of studies of neutron stars in binary systems. He is interested in the way the stars in such systems interact, often in the environment of extreme physics : extreme temperatures, magnetic fields & gravity. He is primarily an observational astronomer experienced in using telescopes at many different wavelengths - these are essential tools for gathering all the pieces of the cosmic jig-saw puzzle to understand these complex systems. He has recently started making use of Smooth Particle Hydrodynamic simulations to try and represent the interactions between the intense point-like gravitational field of the neutron star and the massive circumstellar disks that surround many young stars.