Iota Orionis

The designations of the three constituents as Iota Orionis A, B and C, and those of A's components - Iota Orionis Aa1, Aa2, and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).

[12] The system has the traditional name Nair al Saif, from the Arabic نير السيف nayyir as-sayf "the Bright One of the Sword", though this is little used.

The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.

[3][8] Iota Orionis is generally assumed to be associated with the open cluster NGC 1980, which is at a distance of around 400 pc.

However, they may not lie at exactly the same distance and Iota Orionis may have a complex history involving stellar encounters and runaway stars.

In combination with the high eccentricity (e=0.764) of their 29-day orbit, this suggests that the binary system was created through a capture, rather than by being formed together and undergoing a mass transfer.

Iota Orionis B is a B8 giant at 11" (approximately 5,000 AU[9]) which has been shown to be variable, and likely to be a young stellar object.

ι Orionis is the bright star to the right (south) of the Orion Nebula