A variation of the chemical potential covectors that leaves the metric fixed takes the form
where the complicated terms exist solely because of entrainment. The same procedure as in the previous two examples leads to the dispersion relation This is quadratic in The sound speed analysis is local, but its results are seen globally in the analysis of modes of oscillation
of a fluid body. For a neutron star, the full spectrum of modes is quite impressive (see McDermott et
al. [77]): polar (or spheroidal) f-, p-, and g-modes, and the axial (or toroidal) r-modes. Epstein [41] was the
first to suggest that there should be even more modes in superfluid neutron stars because the superfluidity
allows the neutrons to move independently of the protons. Mendell [78] developed this idea further by using
an analogy with coupled pendulums. He argued that the new modes should feature a counter-motion
between the neutrons and protons, i.e. as the neutrons move out radially, say, the protons
will move in. This is in contrast to ordinary fluid motion that would have the neutrons and
protons move in more or less “lock-step”. Analytical and numerical studies [70, 74, 38, 5]
have confirmed this basic picture and the new modes of oscillation are known as superfluid
modes.
http://www.livingreviews.org/lrr-2007-1 | ![]() This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 Germany License. Problems/comments to |