μ Cephei (mu Cephei)

μ Cephei is a variable and multiple supergiant star in the constellation of Cepheus.

μ Cephei visual magnitude is 4.08. Because of its moderate brightness, μ Cephei should be easily visible from locations with dark skyes, while it can be barely visible, or not visible at all, from skyes affected by light pollution.

The table below summarizes the key facts about μ Cephei:

Color of μ Cephei ⬤

Magnitude of μ Cephei 4.08

Class Supergiant

VISIBILITY RIGHT NOW μ Cephei (mu Cephei) is above the horizon from Greenwich, United Kingdom [change]. Altitude: 49°.

Celestial coordinates and finder chart of μ Cephei

μ Cephei is situated north of the celestial equator, as such, it is more easily visible from the northern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of μ Cephei are provided in the following table:

Right Ascension J2000 21h 43m 30s

Declination J2000 +58° 46’ 48”

Galactic Longitude 100.6°

Galactic Latitude 4.32°

Constellation Cepheus

The simplified sky map below shows the position of μ Cephei in the sky:

Simplified finder chart for μ Cephei (mu Cephei).

Visibility of μ Cephei from your location

Location: Greenwich, United Kingdom [change]
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

μ Cephei (mu Cephei) is circumpolar and transits at 09:05 UTC (altitude: 82.7°)

Digitized Sky Survey image of μ Cephei

The image below is a photograph of μ Cephei from the Digitized Sky Survey 2 (DSS2 - see the credits section) taken in the red channel. The area of sky represented in the image is 0.5x0.5 degrees (30x30 arcmins). The proper motion of μ Cephei is 0.003 arcsec per year in Right Ascension and -0.003 arcsec per year in Declination and the associated displacement for the next 100000 years is represented with the red arrow.

DSS2 image of μ Cephei. The red arrow shows the motion of μ Cephei during the next 100000 years (5.00 arcmin in Right Ascension and -5.00 arcmin in declination);

Distance of μ Cephei from the Sun and relative movement

μ Cephei is distant 5,258.06 light years from the Sun and it is moving far from the Sun at the speed of 19 kilometers per second.

Distance (parsec) 1,612.90 pc

Distance (light year) 5,258.06 ly

Heliocentric radial velocity 19 km/s

Proper Motion RA 0.003 arcsec/year

Proper Motion Dec -0.003 arcsec/year

Spectral properties of μ Cephei

μ Cephei belongs to spectral class M2 and has a luminosity class of I corresponding to a supergiant star.

Absolute magnitude -6.96

Spectral Type M2I

Color Index (B-V) 2.35

Temperature of μ Cephei 2845K

The red dot in the diagram below shows where μ Cephei is situated in the Hertzsprung–Russell diagram.

H-R diagram showing the position of μ Cephei. Attribution: Richard Powell / CC BY-SA

μ Cephei star system properties

μ Cephei is a visual double star which can be observed only with the help of very large telescopes. The table below shows key information about the μ Cephei double sysyem:

Main star magnitude 4.08

Secondary star magnitude 12.38

Magnitude difference 8.3

Separation 19.5 arcsec

Alternative designations of μ Cephei

Bayer designation μ Cephei
(mu Cephei)

Henry Draper Catalogue HD206936

SAO Catalogue SAO33693

Hipparcos Catalogue HIP107259

Durchmusterung Catalogue BD+58 2316

General Catalogue of Variable Stars Mu Cep

Aitken Double Star Catalogue ADS15271

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Other stars in Cepheus