NGC 559, Open Star Cluster
NGC 559 is one of many open star clusters in the constellation Cassiopeia. It is about 4,000 light-years away from Earth and has an apparent diameter
of 6 arcminutes. Therefore the true diameter is about 7 lightyears. With an apparent visual magnitude of 9.5mag it belongs to the fainter star clusters.
The light of the stars is clearly reddened and weakened by dust clouds in front of it. The value for the color excess E(B-V) is 1.64 - this means a
weakening of the starlight by almost 5 magnitudes. The best known dark clouds in the immediate vicinity of NGC 559 are LDN 1325 and LDN 1326.
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With an aperture of 20", the cluster appears like fine star dust at a magnification of 120x and is easy to see both directly and indirectly. A few brighter
stars also stand out immediately.
But NGC 559 becomes really interesting at a magnification of 270x. Then about 70 faint single stars of different brightness can be seen against the dark
sky background. The shape of the cluster is quite irregular and dominated by darker spots and star knots. Most of the stars are in the southern part of the
cluster, while the northern section appears rather star-poor. Near the center there is a narrow double star. The cluster appears completely resolved, no
grainy background or faint background glow can be seen.
