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IR Cephei - HD208960 - HIP108426

IR Cephei is a white to yellow pulsating star that can be located in the constellation of Cepheus. HIP108426 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD208960. IR Cephei has alternative name(s), IR_Cep.

Location of IR Cephei

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 IR Cephei, the location is 21h 57m 51.93 and +61d01`07.9 .

Proper Motion of IR Cephei

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 -003.49 ± 000.31 towards the north and -004.87 ± 000.37 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of IR Cephei

IR Cephei has a spectral type of G0. This means the star is a white to yellow star. The star has a B-V Colour Index of 0.84 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,331 Kelvin.

IR Cephei has been calculated as 21.35 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 14,851,991.79.km.

IR Cephei Apparent and Absolute Magnitudes

IR Cephei has an apparent magnitude of 7.85 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 -1.45 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.30. 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 IR Cephei

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.38 which gave the calculated distance to IR Cephei as 2363.50 light years away from Earth or 724.64 parsecs. It would take a spaceship travelling at the speed of light, 2363.50 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 1.48 which put IR Cephei at a distance of 2203.81 light years or 675.68 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Variable Type of IR Cephei

The star is a pulsating Delta Cepheid variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. IR Cephei brightness ranges from a magnitude of 8.000 to a magnitude of 8.000 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 2.0 days (variability).

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.

IR Cephei Facts

Alternative Names

Traditional NameIR Cephei
Short NameIR Cep
Hipparcos Library I.D.108426
Bonner DurchmusterungBD+60 2321
Henry Draper Designation208960

Visual Facts

Star Type star
Absolute Magnitude-1.45 / -1.30
Apparent Magnitude7.85
Right Ascension (R.A.)21h 57m 51.93
Declination (Dec.)+61d01`07.9
1997 Distance from Earth1.38 Parallax (milliarcseconds)
 2363.50 Light Years
 724.64 Parsecs
2007 Revised Distance from Earth1.48 Parallax (milliarcseconds)
 2203.81 Light Years
 675.68 Parsecs
Proper Motion Dec.-3.49 ± 0.31 milliarcseconds/year
Proper Motion RA.-4.87 ± 0.37 milliarcseconds/year
B-V Index0.84
Spectral TypeG0
Colour(G) White to Yellow

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeDelta Cepheid
Mean Variability Period in Days2.000

Estimated Facts

Radius (x the Sun)21.35
Calculated Effective Temperature5,331 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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
208960+60 2321.0A8.300000.000004.00000G0Yellow
B8.300001968

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