The proton drip-line nucleus Ne-17 is studied in a three-body model of
O-15 plus two protons. The Ne-17 nucleus has a Borromean binding stru
cture, and calculations show arms matter radius of 2.77-2.81 fm, in ag
reement with experiment. The model gives a proton radius excess about
0.26-0.32 fm over the neutron radius, showing that a proton skin is pr
esent. The 73% probability of a valence proton being outside the rms c
ore radius is sufficiently large, however, to indicate a halo. Predict
ions for the momentum distributions of O-15 fragments are given, and t
hese, if verified, would also suggest a two-proton halo structure for
Ne-17. This would be the first identification of a two-proton halo nuc
leus.