Nuclear solid crust on rotating strange quark stars

Abstract

The thickness, mass, and moment of inertia of the nuclear solid crust that can exist on the surface of a rotating strange quark star suspended out of contact with the quark core by an electric dipole layer on the core surface and the centrifugal force is calculated. The question of whether strange stars can undergo the observed phenomena of pulsar glitches is addressed. It is found that the nuclear crust can have a moment of inertia sufficiently large that a fractional change can account for the magnitude of pulsar glitches, even giant glitches. The particular sequence of stars, both rotating and stationary, that have the maximum possible crust density, the neutron drip density, is studied. The sequence has a minimum mass of about 0.015 solar mass. Stars near this limit have crusts of thickness tens to hundreds of kilometers and are small and dark and thus could be hiding places of baryonic matter.