Mu Cephei is also known as Erakis or μ Cep. The star is also commonly known as Herschel's Garnet Star after William Herschel's description of the visual appearance of the star.
Mu Cephei is listed in SIMBAD as being a red supergiant rather than a standard carbon star. The star has depleted the hydrogen in it's core and it is now fusing helium into carbon, which causes the distinctive red coloration. So in that respect, it meets the basic criteria for being a carbon star, and as a supergiant, it is one of the largest.
Mu Cephei is magnitude 4.08 in the V band so it visible to the naked eye, but just barely from most urban locations. Observing the star with a telescope or binoculars reveals the striking red color.
This star is is one of the largest known visible stars. It has been described as a hypergiant. μ Cep is a popular and attractive star for visual observations. It is nearing the end of it's life and in it's final moments it may produce a supernova that results in a black hole.
The spectral type of μ Cep is listed as M2-Ia and it is the standard star for that class. The star is estimated to be between 1,333 and 2,857 parsecs distant, a rather wide variation. So it's actual distance to us is somewhat uncertain.
