Cepheus

Cepheus is a constellation in the northern sky. It is named after Cepheus, King of Aethiopia in Greek mythology. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest star is Alpha Cephei with an apparent magnitude of 3.5. Delta Cephei is the prototype of an important class of star known as a Cepheid variable. Mu Cephei and VV Cephei are red supergiants and among the largest of stars. ... Stars. Alpha Cephei, traditionally called Alderamin, is a white hued star of magnitude 2.5, 49 light-years from Earth. Beta Cephei, traditionally called "Alfirk", is a double star with a blue-hued giant primary of magnitude 3.2 and a secondary of magnitude 7.9. The primary is a variable star considered to be the prototype of its subclass of pulsating variable stars, which are sometimes named for Beta Canis Majoris. Beta Cephei variables do not have wide ranges in magnitude, nor do they have periods longer than a few hours. Beta Cephei itself varies 0.1 magnitudes every 4.6 hours. Its traditional name means "flock" and refers to a flock of sheep. Gamma Cephei, traditionally called Errai, is an orange-hued star of magnitude 3.2, 45 light-years from Earth. Its traditional name means "the shepherd". It is a binary star approximately 50 light years away from Earth. The system consists of an orange subgiant and a red dwarf. Due to the precession of the equinoxes, γ Cephei will be the pole star between AD 3000 and 5200, with the closest approach to the celestial pole around AD 4000. The primary component is orbited by a planet. Delta Cephei is the prototype Cepheid variable, a yellow-hued supergiant star 980 light-years from Earth. It was discovered to be variable by John Goodricke in 1784. It varies between 3.5m and 4.4m over a period of 5 days and 9 hours. The Cepheids are a class of pulsating variable stars; Delta Cephei has a minimum size of 40 solar diameters and a maximum size of 46 solar diameters. It is also a double star; the yellow star also has a wide-set blue-hued companion of magnitude 6.3. ... Deep-sky objects. NGC 188 is an open cluster that has the distinction of being the closest open cluster to the north celestial pole, as well as one of the oldest known open clusters. The Fireworks Galaxy (NGC 6946) is a spiral galaxy in which nine supernovae have been observed, more than in any other galaxy. IC 469 is another spiral galaxy, characterized by a compact nucleus, of oval shape, with perceptible side arms. The nebula NGC 7538 is home to the largest yet discovered protostar. NGC 7023 is a reflection nebula with an associated star cluster (Collinder 429); it has an overall magnitude of 7.7 and is 1400 light-years from Earth. The nebula and cluster are located near Beta Cephei and T Cephei. [Cepheus (constellation). Wikipedia]