MG11 
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The eigenmode frequency distribution of rapidly rotating neutron stars

Among the most promising sources of gravitational waves from neutron stars are non-radial oscillations, and especially the rotation-driven ones (inertial modes) that can be unstable for a large range of rotation rates and temperatures. By performing mode calculation for rapidly rotating neutron stars we find that the inertial modes of a specific azimuthal index are confined, in contrast to the pressure-driven modes, to a finite, well-defined frequency range, whose width depends on the spin frequency and the compactness of the star. Their apparently dense frequency distribution raises again the question of a continuous spectrum; this still allows, however, individual modes to be identified, with most interesting one being the fundamental r-mode.

A unique test for QPO models and masses of neutron stars in LMXBs

The discovery of twin kHz QPOs from the peculiar LMXB Circinus X-1 and the correlations among their frequencies not only proves the existence of an underlying neutron star but also provides a unique test for QPO models. The observation for the first time of a decreasing peak seperation with decreasing kHz QPO frequency and the extended range of kHz QPO frequencies places strong constrains on theoretical models and confirms predictions of few of them. Least square fits supports a mass much higher then the observed ones from isolated neutron stars.