  We use halo effective field theory to analyze the universal features of
proton halo nuclei bound due to a large S-wave scattering length. With a
Lagrangian built from effective core and valence-proton fields, we derive a
leading-order expression for the charge form factor. Within the same framework
we also calculate the radiative proton capture cross section. Our general
results at leading order are applied to study the excited 1/2+ state of
Fluorine-17, and we give results for the charge radius and the astrophysical
S-factor.
