Let G be a connected semisimple algebraic group over an algebraically
closed field of characteristic zero, and let th be an automorphism of G.
We give a characterization of th-twisted spherical conjugacy classes in G
by a formula for their dimensions in terms of certain elements in the Weyl
group of G, generalizing a result of N. Cantarini, G. Carnovale, and M.
Costantini when th is the identity automorphism. For G simple and th an
outer automorphism of G, we also classify the Weyl group elements that appear
in the dimension formula.Comment: 8 page