I always thought that p-orbitals had a dumbbell shape as pictured below.
However, I was reading an article (see Table 1, item 2) that says, "...the spherical $\mathrm{p_{1/2}}$ subshell..." (my emphasis). The implication being that the $\mathrm{p_{1/2}}$ orbital (subshell?) has a greater electron density near the nucleus thenthan the $\mathrm{p_{3/2}}$ orbital (subshell?). Why is this andand why do they call the $\mathrm{p_{1/2}}$ orbital spherical?