Universe Guide


SS Cep, HD22689, HIP17881

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

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.

Location of SS Cep

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 SS Cep, the location is 03h 49m 30.03 and +80d19`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.

Physical Properties (Colour, Temperature, Radius) of SS Cep

SS Cep has a spectral type of M5IIIvar. This means the star is a red giant star. The star is 7557.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24648.1639060800000000s. 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. 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.

SS Cep Facts

Alternative Names

Traditional/Proper NameSS Cep
Short NameSS Cep
Hipparcos Library I.D.17881
Bonner DurchmusterungBD+79 110
Henry Draper Designation22689

Visual Facts

Star Typegiant star
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.)+80d19`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 Revised 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
Spectral TypeM5IIIvar
Colour(M) Red

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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