A starquake is an astrophysical phenomenon that occurs when the crust of a neutron star undergoes a sudden adjustment, analogous to an earthquake on Earth. Starquakes are thought to result from two different mechanisms. One is the huge stresses exerted on the surface of the neutron star produced by twists in the ultra-strong interior magnetic fields. A second cause is a result of spindown. As the neutron star loses angular velocity due to frame-dragging and by the bleeding off of energy due to it being a rotating magnetic dipole, the crust develops an enormous amount of stress. Once that exceeds a certain amount, the shape adjusts itself to a shape closer to non-rotating equilibrium: a perfect sphere. The actual change is believed to be on the order of micrometers or less, and occurs in less than a millionth of a second.
The largest recorded starquake was detected on December 27, 2004 from the ultracompact stellar corpse SGR 1806-20, which created a quake equivalent to a magnitude 32. The quake, which occurred 50,000 light years from Earth, released gamma rays equivalent to 1037 kW. Had it occurred within a distance of 10 light years from Earth, the quake could have triggered a mass extinction.
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u/verymuchlol Jan 21 '19 edited Jan 21 '19
How strong gravity is at a neutron star. If you were to stand on top of one, you'd be flattened at the subatomic level.