Alpha Centauri

Alpha Centauri, also known as Rigil Kentaurus is the closest star to Earth, after the Sun. In several continuities, the Alpha Centauri star system is established as home to Cybertron.

Marvel Comics continuity
Cybertron originally orbited around Alpha Centauri, before the forces released by the Autobot-Decepticon war tore the planet from its place in space and sent it spiralling off through the galaxy.

S.T.A.R.S. continuity
Cybertron originally orbited around Alpha Centauri, before the forces released by the Autobot-Decepticon war tore the planet from its place in space and sent it spiralling off through the galaxy.

Dreamwave Generation One continuity
Cybertron continues to orbit Alpha Centauri in the present day.

Transformers: War for Cybertron
Cybertron resided in the Alpha Centauri star system, according to sneak preview video transmissions.