Modelling the Accretion Process in Intermediate Polars

Taylor, Peter (1998). Modelling the Accretion Process in Intermediate Polars. PhD thesis The Open University.



Intermediate Polars form a subclass of the cataclysmic variables, wherein a white dwarf accretes material from a main sequence star. They are inferred to have a magnetic field of ≥ 106 G which has observable effects on the accretion, in particular whether it occurs mainly through a truncated disc, or directly via a stream. The result is pulsed X-ray emissions, caused by occultation of the bright area, and absorption of the X-rays. The project concerning this thesis is to develop a computer model to simulate these pulses using the assumed physics involved, hence to constrain the physical parameters for particular systems.

This thesis starts in Chapter 1 with an introduction to intermediate polars, setting them in context, and pointing out some of the unknown quantities and problems involved with them. Chapter 2 briefly describes some of the instrumentation used to obtain the data, and gives examples of X-ray data from some of the systems. Chapter 3 gives a more detailed examination of two particular objects, AO Psc and V1223 Sgr, using observations from the Ginga and ROSAT satellites, and concludes that both have a high inclination, and are predominantly disc-fed. Chapter 4 is the core of the thesis, in which some of the work discussed in Chapter 1 is taken further, with a detailed re-evaluation of the geometry involved, and how these are incorporated into the computer simulation. The results of using this are discussed in Chapter 5, although its use up to the present has been in investigating the parameter space rather than formally fitting to known systems. Chapter 6 discusses this latter possibility, and considers enhancements which would be useful to include. Also in this final chapter, a brief comparison to another model from a different research team is made.

Viewing alternatives

Download history


Public Attention

Altmetrics from Altmetric

Number of Citations

Citations from Dimensions

Item Actions