*R or R* denote hyperreal numbers.
R* may also refer to:
R* rule (ecology), or resource-ratio hypothesis, a hypothesis in community ecology Rockstar Games, an American video game publisher r* or r-star, natural rate of interest R*-tree, a tree data structure for spatial access Rstar, later called Okina, a sub-satellite of SELENE
See also Berkeley r-commands, to enable Unix users to issue commands to another Unix computer via TCP/IP computer network Carbon star Variable star