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A super star cluster (SSC) is a very massive young open cluster that is thought to be the precursor of a globular cluster. [1] These clusters called "super" because they are relatively more luminous and contain more mass than other young star clusters. [ 2 ]
Cluster analysis or clustering is the task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some specific sense defined by the analyst) to each other than to those in other groups (clusters).
The Sagittarius A* cluster is the cluster of stars in close orbit around Sagittarius A*, the supermassive black hole at the center of the Milky Way (in the Galactic Center). The individual stars are often listed as " S-stars ", but their names and IDs are not formalized, and stars can have different numbers in different catalogues .
Cluster grouping is not experimental as it has been used successfully since 1974. [2] While no single practice is a panacea for gifted instruction, Schuler's national survey showed a 99% positive approval rating among parents of clustered children and a 90% positive approval rating among the children themselves.
The method is also known as nearest neighbour clustering. The result of the clustering can be visualized as a dendrogram, which shows the sequence in which clusters were merged and the distance at which each merge took place. [3] Mathematically, the linkage function – the distance D(X,Y) between clusters X and Y – is described by the expression
The silhouette value is a measure of how similar an object is to its own cluster (cohesion) compared to other clusters (separation). The silhouette ranges from −1 to +1, where a high value indicates that the object is well matched to its own cluster and poorly matched to neighboring clusters.
Abt — (for example: open star cluster Abt 1 = Biurakan 4 = Markarian 6 = Stock 7) (at 2:29.6 / +60°39' near the southwestern section of the Heart Nebula in Cassiopeia) AC — Astrographic Catalogue; A.C. — Alvan Clark (double stars) Ac / Ack — Agnès Acker (planetary nebulae) A.G.C. — Alvan Graham Clark (double stars) AGC — Arecibo ...
Because the minimization over all possible sets of cluster centers is prohibitively complex, the distortion is computed in practice by generating a set of cluster centers using a standard clustering algorithm and computing the distortion using the result. The pseudo-code for the jump method with an input set of p-dimensional data points X is:
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