Neutron stars have "hair". At least they do in comparison with black holes, according to the famous "no hair" conjecture made by John Wheeler of Princeton University in the US in the 1960s. A neutron star's "hair" is the detailed activity caused by its strong magnetic fields, and the seismic-like activity that occurs in its crust. Thus, while a black hole may be described with textbook simplicity using only its mass, charge and angular momentum, each neutron star is complex, unique and phenomenologically rich.
Now Ingrid Stairs, Andrew Lyne and Setnam Shemar of the University of Manchester in the UK have shown that at least one rotating neutron star manifests its structure as a wobble of its spin axis (Nature 2000 406 484).
James M Cordes of the National Astronomy and Ionosphere Center, Cornell University, USA, reveals in the October issue of Physics World why this result is so interesting and important.