It was an extremely powerful magnetic field that surrounded Rigel A and extended to a distance of approximately 80 AU from it. The belt acted as a shield against the lethal doses of ionizing radiation emitted by the star, a B class blue-white supergiant, one of the biggest, hottest, and brightest of stars.
In this way, the Hakel radiation belt protected the rest of the Rigel system, including its worlds and inhabitants, against the star's radiation. The surprising number of Class M planets in the Rigel system was attributed to the Hakel radiation, as well as to the wide range of orbits conducive to life that the star supported. (ST references: Star Trek Maps, The Worlds of the Federation) The environment within the zone was extremely deadly.
The belt also caused severe magnetic disturbances in front of it, near the orbit of Rigel I, and these were very hazardous to ships and the automated mining equipment on that planet. They occasionally damaged the Orion mining facility's computer controls, and volunteer engineers in protective armor would arrive in heavily shielded ships to make repairs in the highly dangerous environment. (FASA RPG module: The Orions: Book of Common Knowledge)
- The Hakel radiation belt was named the Hakiel Radiation Zone in The Orions: Book of Common Knowledge, perhaps in error.