  In the present paper we study the oscillation spectrum of neutron stars
containing both ordinary matter and dark energy in different proportions.
Within the model we consider, the equilibrium configurations are numerically
constructed and the results show that the properties of the mixed
neuron-dark-energy star can differ significantly when the amount of dark energy
in the stars is varied. The oscillations of the mixed neuron-dark-energy stars
are studied in the Cowling approximation. As a result we find that the
frequencies of the fundamental mode and the higher overtones are strongly
affected by the dark energy content. This can be used in the future to detect
the presence of dark energy in the neutron stars and to constrain the
dark-energy models.
