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SS Cep, HD22689, HIP17881

SS Cep is a red pulsating giant star that can be located in the constellation of Cepheus. The description is based on the spectral class. The star can not be seen by the naked eye, you need a telescope to see it.

SS Cep's Alternative Names

HIP17881 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD22689.

SS Cep has alternative name(s) :- , SS Cep.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+79 110.

More details on star alternative names can be found at Star Names .

Location of SS Cep

The location of the star in the night sky 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 SS Cep, the location is 03h 49m 30.03 and +80° 19` 20.8 .

Proper Motion of SS Cep

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 14.14 ± 0.42 miliarcseconds/year towards the north and -5.00 ± 0.49 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is -46.89000 km/s with an error of about 0.17 km/s .

SS Cep Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 136.89 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of SS Cep

SS Cep has a spectral type of M5IIIvar. This means the star is a red giant star. The star is 7,557.00 Parsecs from the Galactic Centre or terms of Light Years is 24,648.16 s. The star has a B-V Colour Index of 1.22 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,455 Kelvin.

SS Cep Radius has been calculated as being 14.36 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 9,992,877.15.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 15.04. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

SS Cep Apparent and Absolute Magnitudes

SS Cep has an apparent magnitude of 7.16 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 0.19 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.09. 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 SS Cep

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.04 which gave the calculated distance to SS Cep as 807.34 light years away from Earth or 247.52 parsecs. It would take a spaceship travelling at the speed of light, 807.34 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 3.85 which put SS Cep at a distance of 847.18 light years or 259.74 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.

The star's Galacto-Centric Distance is 7,557.00 Parsecs or 24,648.16 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of SS Cep

The star is a pulsating Slow Irregular 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. SS Cep brightness ranges from a magnitude of 6.947 to a magnitude of 6.370 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.5 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 Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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SS Cep Facts

Visual Facts


Primary / Proper / Traditional NameSS Cep
Alternative NamesHD 22689, HIP 17881, BD+79 110, SS Cep
Spectral TypeM5IIIvar
Multiple Star SystemNo / Unknown
Star TypeGiant Star
Colour red
GalaxyMilky Way
ConstellationCepheus
Absolute Magnitude0.19 / 0.09
Visual / Apparent Magnitude7.16
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)03h 49m 30.03
Declination (Dec.)+80° 19` 20.8
Galactic Latitude20.05 degrees
Galactic Longitude130.14 degrees
1997 Distance from Earth4.04 Parallax (milliarcseconds)
 807.34 Light Years
 247.52 Parsecs
2007 Distance from Earth3.85 Parallax (milliarcseconds)
 847.18 Light Years
 259.74 Parsecs
Galacto-Centric Distance24,648.16 Light Years / 7,557.00 Parsecs
Proper Motion Dec.14.14 ± 0.42 milliarcseconds/year
Proper Motion RA.-5.00 ± 0.49 milliarcseconds/year
B-V Index1.22
Radial Velocity-46.89 ± 0.17 km/s
Eccentricity0.25
Semi-Major Axis7235.00
Stellar Luminosity (Lsun)136.89

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.529
Variable Magnitude Range (Brighter - Dimmer)6.370 - 6.947

Estimated Facts


Calculated Effective Temperature4,455 Kelvin

Sources and Links


SIMBAD SourceLink

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