Changes

Rigel B is a class B9 V star of magnitude 6.7, making it just slightly too dim to be seen with the unaided eye, even if the star was alone.<ref name="peter">Jedicke, Peter; Levy, David H. (1992). "Regal Rigel". The New Cosmos. Waukesha: Kalmbach Books. pp. 48–53.</ref>  Because Rigel A is some 500 times as bright, Rigel B is obscured by its companion, making observations challenging. Rigel B itself is some 2500 AU from its primary (or some 60 times the distance Pluto is from the Sun) taking 25,000 years to orbit.<ref name="illinois">http://www.astro.illinois.edu/~jkaler/sow/rigel.html</ref>

Rigel B is a class B9 V star of magnitude 6.7, making it just slightly too dim to be seen with the unaided eye, even if the star was alone.<ref name="peter">Jedicke, Peter; Levy, David H. (1992). "Regal Rigel". The New Cosmos. Waukesha: Kalmbach Books. pp. 48–53.</ref>  Because Rigel A is some 500 times as bright, Rigel B is obscured by its companion, making observations challenging. Rigel B itself is some 2500 AU from its primary (or some 60 times the distance Pluto is from the Sun) taking 25,000 years to orbit.<ref name="illinois">http://www.astro.illinois.edu/~jkaler/sow/rigel.html</ref>

Some astronomers have claimed that Rigel B itself is actually is double, and if so would more accurately be called Rigel BC.  However the idea of Rigel B being a double star in itself is still highly controversial, with proponents unable to repeatedly duplicate their initial results.<ref name="peter">Jedicke, Peter; Levy, David H. (1992). "Regal Rigel". The New Cosmos. Waukesha: Kalmbach Books. pp. 48–53.</ref>

Some astronomers have claimed that Rigel B itself is actually a double, and if so would more accurately be called Rigel BC.  However the idea of Rigel B being a double star in itself is still highly controversial, with proponents unable to repeatedly duplicate their initial results.<ref name="peter">Jedicke, Peter; Levy, David H. (1992). "Regal Rigel". The New Cosmos. Waukesha: Kalmbach Books. pp. 48–53.</ref>

There is also a 15th magnitude class K star, referred to as Rigel D, believed to be associated with the other stars of the Rigel system.  It is estimated to be some 11,500 AU from Rigel A and its companion, and if part of the system, would take some 250,000 years to orbit the primary.<ref name="illinois">http://www.astro.illinois.edu/~jkaler/sow/rigel.html</ref>

There is also a 15th magnitude class K star, referred to as Rigel D, believed to be associated with the other stars of the Rigel system.  It is estimated to be some 11,500 AU from Rigel A and its companion, and if part of the system, would take some 250,000 years to orbit the primary.<ref name="illinois">http://www.astro.illinois.edu/~jkaler/sow/rigel.html</ref>