History and mythology Ĭepheus was the King of Aethiopia. In addition, Cepheus also has the hyperluminous quasar S5 0014+81, which hosts an ultramassive black hole in its core, reported at 40 billion solar masses, about 10,000 times more massive than the central black hole of the Milky Way, making this among the most massive black holes currently known. RW Cephei, an orange hypergiant, together with the red supergiants Mu Cephei, MY Cephei, VV Cephei, and V354 Cephei are among the largest stars known. Delta Cephei is the prototype of an important class of star known as a Cepheid variable. The constellation's brightest star is Alpha Cephei, with an apparent magnitude of 2.5.
It is one of the 48 constellations listed by the second century astronomer Ptolemy, and it remains one of the 88 constellations in the modern times. Visible at latitudes between + 90° and − 10°.īest visible at 21:00 (9 p.m.) during the month of November.Ĭepheus is a constellation in the far northern sky, named after Cepheus, a king of Aethiopia in Greek mythology.
