Iota Cassiopeiae (ι Cas / HD 15089 / HR 707) is a stellar system in the constellation Cassiopeia. It is about 142 light years from the solar system.
With a small telescope you can see a triple star system. The brightest star (Iota Cassiopeiae A) is a white star of apparent magnitude +4.64 of peculiar spectral type A5. At 2,7 seconds of arc is Iota Cassiopeiae B, of spectral type F5 and magnitude +6,89. At 7.4 arc seconds, the weakest of the three, Iota Cassiopeiae C, is a spectral type yellow dwarf G7V and magnitude +8.40. It is interesting to note the contrast between components A and B, almost white, and component C, orange.
Iota Cassiopeiae A is a slightly variable star of the Alfa2 Canum Venaticorum type, with variations in magnitude from +4,45 to +4,53 over a period of 1.74 days. It has a very close companion star, only 0.5 seconds of arc, with an orbital period of 47. It receives the name of Iota Cassiopeiae Aa and is of spectral type G2. On the other hand, multiple observations of the system seem to indicate that Iota Cassiopeiae B moves in a straight line, being able not to be a star of the system, but simply a step star.
Iota Cassiopeiae C is too far away to study its orbit. In turn, it has been discovered that it has a companion close to 0.4 seconds of arc, Iota Cassiopeiae c, spectral type K5.
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