Your guide to the Solar System and the night sky
🌎 Location: Greenwich, United Kingdom [change]

Alfirk - β Cephei (beta Cephei)

Alfirk, also designated as β Cephei (beta Cephei), is a variable and multiple sub-giant star in the constellation of Cepheus.

Alfirk visual magnitude is 3.23. Because of its moderate brightness, Alfirk 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 Alfirk:

3.23
Sub-giant
Alfirk - β Cephei (beta Cephei) is above the horizon from Greenwich, United Kingdom [change]. Altitude: 54°.

Celestial coordinates and finder chart of Alfirk

Alfirk is situated close to the northern celestial pole and, as such, it is visible for most part of the year from the northern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of Alfirk are provided in the following table:

21h 28m 39s
+70° 33’ 38”
107.54°
14.03°
Cepheus

The simplified sky map below shows the position of Alfirk in the sky:

Finder chart Alfirk - β Cephei (beta Cephei) star
Simplified finder chart for Alfirk - β Cephei (beta Cephei).

Visibility of Alfirk from your location

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

Alfirk - β Cephei (beta Cephei) is circumpolar and transits at 02:26 UTC (altitude: 70.9°)

Digitized Sky Survey image of Alfirk

The image below is a photograph of Alfirk 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 Alfirk is 0.01 arcsec per year in Right Ascension and 0.007 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of Alfirk - β Cephei (beta Cephei) star
DSS2 image of Alfirk. The red arrow shows the motion of Alfirk during the next 10000 years (1.67 arcmin in Right Ascension and 1.17 arcmin in declination);

Distance of Alfirk from the Sun and relative movement

Alfirk is distant 594.89 light years from the Sun and it is moving towards the Sun at the speed of 8 kilometers per second.

182.48 pc
594.89 ly
-8 km/s
0.01 arcsec/year
0.007 arcsec/year

Spectral properties of Alfirk

Alfirk belongs to spectral class B1 and has a luminosity class of IV corresponding to a sub-giant star.

-3.08
B1IV
14087K

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

HR Diagram
H-R diagram showing the position of Alfirk. Attribution: Richard Powell / CC BY-SA

Alfirk star system properties

Alfirk is a visual double star which can be observed with the help of small or medium telescopes. The table below shows key information about the Alfirk double sysyem:

3.23
7.83
4.6
13.4 arcsec

Alternative designations of Alfirk

Alfirk
β Cephei
(beta Cephei)
SAO10057
SAO10057