  In bulk non-centrosymmetric magnets the chiral Dzyaloshinskii-Moriya exchange
stabilizes tubular skyrmions with a reversed magnetization in their centers.
While the double-twist is favorable in the center of a skyrmion, it gives rise
to an excess of the energy density at the outskirt. Therefore, magnetic
anisotropies are required to make skyrmions more favorable than the conical
spiral state in bulk materials. Using Monte Carlo simulations, we show that in
magnetic nanowires unusual skyrmions with a doubly twisted core and a number of
concentric helicoidal undulations (target-skyrmions) are thermodynamically
stable even in absence of single-ion anisotropies. Such skyrmions are free of
magnetic charges and, since the angle describing the direction of magnetization
at the surface depends on the radius of the nanowire and an applied magnetic
field, they carry a non-integer skyrmion charge s > 1. This state competes with
clusters of spatially separated s=1 skyrmions. For very small radii, the
target-skyrmion transforms into a skyrmion with s < 1, that resembles the
vortex-like state stabilized by surface-induced anisotropies.
