MY Cephei is a very luminous Supergiant Star type star. It is a red supergiant star located in the Cepheus constellation. It is a semiregular variable star with a maximum brightness of magnitude 14.4 and a minimum of magnitude 15.5. It is 1,134 times larger than the Sun. It is not part of the Cepheus constellation outline but is within the borders of the constellation. The star is roughly 222,170,400.00 Astronomical Units from the Earth/Sun give or take a few.
MY Cephei has an unusual spectral type of M7.5, one of the latest spectral types of any supergiant, and is one of the most luminous and coolest red supergiants, as well as one of the largest known stars. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. If placed at the center of the Solar System, the star’s surface would engulf the orbit of Jupiter and possibly even the orbit of Saturn. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.
The location of the supergiant star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. Observations of the open cluster NGC 7419 in 1954 showed that four of its members were luminous red stars, most likely red supergiants. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. In addition, an unusually red star was found to be variable and probably an even more luminous supergiant. This star was given the variable star designation MY Cephei in 1973 in the 59th name-list of variable stars.
All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. MY Cephei is classified as semiregular variable star of sub-type SRc, indicating it is a cool supergiant, although its pulsational period is not known. In the case of a star, its the galactic centre. It has been observed as bright as magnitude 14.4 and as faint as magnitude 15.5. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. The star, along with another late red supergiant star, S Persei, are sometimes considered prototypes for the class of M6–7 supergiants. Proper Motion details the movements of these stars and are measured in milliarcseconds.