QPO essays

QPO essays In the analysis of GK Per, a strange phenomenon can be observed ¡Xquasi-periodic oscillations (QPO).  ¡QPOs are defined as low-coherence brightness oscillations thought to be associated with material within the inner accretion flows of CVs (Morales-Rueda, Still No consensus has been reached as to a single model for the QPO phenomenon. Theoretical models suggest dense blobs in orbit within the inner disk (Bath 1973), pulsations on the surface of the white dwarf (Papaloizou Godon 1995). However, these models can only account for QPOs of a few hundred seconds. GK Per, on the other hand, has a QPO of several thousand seconds (MSR 1999). To explain this problem, several new models were developed. MSR (1999) apply the magnetospheric ¡Xor beat-frequency ¡Xmodel suggested by Watson, King & Osbourne (1985). Since GK Per has a relatively weak magnetic field, the accretion disk will come very close to the star, completely surrounding the magnetic field. At the inner edge, clumps of plasma will be present. The magnetosphere will keep the clumps from coming closer to the star ¡Xunless the clump moves directly above the poles. When this occurs, t...