- Cepheus was the mythological king of Ethiopia. He was deemed worthy of a place in the sky because he was fourth in descent from the nymph Io, one of the loves of Zeus – and having Zeus as a relative was always an advantage when it came to being commemorated among the constellations. The kingdom of Cepheus was not the Ethiopia we know today, but stretched from the south-eastern shore of the Mediterranean southwards to the Red Sea, an area that contains parts of the modern Israel, Jordan, and Egypt. Ptolemy described him as wearing the tiara-like head-dress of a Persian king, as he is shown on John Flamsteed’s star atlas…
- Open cluster (Wikipedia)
An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and many more are thought to exist. Each one is loosely bound by mutual gravitational attraction and becomes disrupted by close encounters with other clusters and clouds of gas as they orbit the Galactic Center. This can result in a loss of cluster members through internal close encounters and a dispersion into the main body of the galaxy. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members, and can survive for longer. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring.