R. Maartens et al., GENERAL-SOLUTION AND CLASSIFICATION OF CONFORMAL MOTIONS IN STATIC SPHERICAL SPACETIMES, Classical and quantum gravity, 12(10), 1995, pp. 2577-2586
We find the complete and explicit general solution of the conformal Ki
lling equation in static spherically symmetric spacetimes, thus unifyi
ng and generalizing previous special cases. For non-conformally-kat sp
acetimes, there are at most two proper conformal motions. There are th
ree classes of such spacetimes, and one or both of the conformal Killi
ng vectors is non-inheriting. One of the classes includes self-similar
spacetimes (i.e. with a homothetic motion). The conformally flat spac
etimes (including the Schwarzschild interior metric) fall into three c
lasses, and their eleven proper conformal Killing vectors are given in
full. The only spacetimes with conformal motion that are regular at t
he centre are conformally flat.