  We demonstrate that electrons in quantum dots defined by electrostatic gates
in semiconductor nanotubes freeze orderly in space realizing a `Wigner
molecule'. Our exact diagonalisation calculations uncover the features of the
electron molecule, which may be accessed by tunneling spectroscopy -indeed some
of them have already been observed by Deshpande and Bockrath [Nature Phys. 4,
314 (2008)]. We show that numerical results are satisfactorily reproduced by a
simple ansatz vibrational wave function: electrons have localized wave
functions, like nuclei in an ordinary molecule, whereas low-energy excitations
are collective vibrations of electrons around their equilibrium positions.
