Marsic (Kappa Herculis) -- Double Star in Hercules
Marsic -- Apparent Double Star in Hercules
Not all stars that appear to be doubles are gravitationally bound to each other. Often
doubles are allusions, they appear close together because they just happen to be in
the same line-of-sight and are in reality quite distant from one another. A good example
is Marsic (means elbow). Marsic (Kappa Herculis) appears as a double but the two
stars are separated from one another by 1,630 light years.