51 Pegasi b, a hot jovian world; one of the first extrasolar planets to be named.
The planet shows orbital periods shorter than 15 terran days.
These types of planets were among the first extrasolar planets discovered by Terragen astronomers, during the pre-singularity period (early Information Age). Included in this category are 51 Peg itself, Tau Bootis, 55 Cancri, and Upsilon Andromedae, which have orbital periods of just 4.2, 3.3, 14.7 and 4.6 days, respectively. The orbits are all small, with radii less than 0.1 A.U. They commonly range in mass from 0.44 Jupiters (for 51 Peg) to 3.64 Jupiters (Tau Bootis). They move in circular or near-circular orbits.