It is known that fluid object that it magnetized with a purely poloidal field is unstable to perturbations that overturn the field lines in one hemisphere relative to those in the other. We have shown that this instability occurs even when the entire object is encased by a solid crust, as conjectured by Flowers and Ruderman (FR) nearly a decade ago. We have derived the exact dispersion relation that displays this instability for an infinite, cylindrical geometry, which will be published

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... e. The timescale for the instability is roughly the ohmic dissipation timescale of the crust.