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Alderamin (Alpha Cephei) - HD203280 - HIP105199 - HR8162

Alderamin (Alpha Cephei) is a blue subgiant star that can be located in the constellation of Cepheus. Alpha Cephei is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR8162. HIP105199 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD203280. Alderamin has alternative name(s), 5 Cephei , 5 Cep.

Location of Alderamin

The location of the star in the galaxy is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. 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. The Declination is how far north or south the star is compared to the celestial equator and is expressed in degrees. For Alderamin, the location is 21h 18m 34.58 and +62d35`07.6 .

Proper Motion of Alderamin

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving 049.09 ± 000.09 towards the north and 150.55 ± 000.11 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Alderamin

Alderamin has a spectral type of A7IV-V. This means the star is a blue subgiant star. The star has a B-V Colour Index of 0.25 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,483 Kelvin.

Alderamin has been calculated as 2.68 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,867,328.94.km.

Alderamin Apparent and Absolute Magnitudes

Alderamin has an apparent magnitude of 2.45 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 1.58 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.56. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to Alderamin

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 66.84 which gave the calculated distance to Alderamin as 48.80 light years away from Earth or 14.96 parsecs. In 2007, Hipparcos data was revised with a new parallax of 66.50 which put Alderamin at a distance of 49.05 light years or 15.04 parsecs.

It would take a spaceship travelling at the speed of light, 48.80 years using the 1997 distance to get there. We don't have the technology or spaceship that can carry people over that distance yet.

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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Alderamin Facts

Alternative Names

Traditional NameAlderamin
Short Name5 Cep
English MeaningThe right forearm ?
Bayer DesignationAlpha Cephei
Alternative Name(s)5 Cephei
Hipparcos Library I.D.105199
Yale Bright Star Catalogue (HR) Id8162
Bonner DurchmusterungBD+61 2111
Henry Draper Designation203280

Visual Facts

Star Typesubgiant star
Absolute Magnitude1.58 / 1.56
Apparent Magnitude2.45
Right Ascension (R.A.)21h 18m 34.58
Declination (Dec.)+62d35`07.6
1997 Distance from Earth66.84 Parallax (milliarcseconds)
 48.80 Light Years
 14.96 Parsecs
2007 Distance from Earth66.50 Parallax (milliarcseconds)
 49.05 Light Years
 15.04 Parsecs
Proper Motion Dec.49.09 ± 0.09 milliarcseconds/year
Proper Motion RA.150.55 ± 0.11 milliarcseconds/year
B-V Index0.25
Spectral TypeA7IV-V
Colour(A) blue

Estimated Facts

Radius (x the Sun)2.68
Calculated Effective Temperature7,483 Kelvin

Sources and Links

SIMBAD SourceLink

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.


Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
203280+61 2111.0A2.60000151.0000052.00000A5White
B10.400001907
BC11.100001907
CD11.300001907

Location of Alderamin in Cepheus


Alderamin (Alpha Cephei) Location in Cepheus

The map was generated using Night Vision, an awesome free application by Brian Simpson.



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