Ket-Cheleb (planet)

Vulcan I was the first planet in the Vulcan system, a small Class B planet in orbit of the star 40 Eridani A. Unlike other bodies in the system Vulcan I's orbit was at a slight angle to the orbital plane. 

Background
Vulcan I also appears in the reference book The Worlds of the Federation, however no details are given other than it being the first planet in the system. Both The Worlds of the Federation and Star Charts show it to be the smallest planet in the system, although it appears to be slightly smaller in Star Charts.