Magnetically channelled flows in stellar systems

This thesis discusses the interaction of stellar magnetic fields with circumstellar material in a variety of situations. Chapter 2 examines models of young stellar objects where accretion from the surrounding disc is controlled by magnetic loop structures on the star. The models produce outflows at early times which are consistent with those observed for young objects and the resultant torque on the star spins it down on a timescale also consistent with observations. Chapter 3 presents models examining the consequences of the magnetic field of the secondary star in Cataclysmic Variables (CVs) for the outburst behaviour of dwarf novae. Resonance phenomena are identified and observational tests suggested along with upper limits for the magnetic fields of the secondaries in SU UMa and U Gem systems. Chapters 4 and 5 examine the general angular momentum evolution of CVs. Simulations of magnetic braking are produced which describe the evolution in different situations. The proposal of reduced magnetic braking in polar systems is examined. Simulations are carried out which suggest that the addition of a strongly magnetic primary actually increases the rate of angular momentum loss from the binary orbit.