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Sigma Cassiopeiae, 8 Cassiopeiae, HD224572, HIP118243

Sigma Cassiopeiae is a blue main sequence dwarf star that can be located in the constellation of Cassiopeia. Sigma Cassiopeiae is the brightest star in Cassiopeia based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Sigma Cassiopeiae is the Bayer Classification for the star. HIP118243 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD224572.

Location of Sigma Cassiopeiae

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 Sigma Cassiopeiae, the location is 23h 59m 00.53 and +55d45`17.8 .

Proper Motion of Sigma Cassiopeiae

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 -5.01 ± 0.29 miliarcseconds/year towards the north and 8.14 ± 0.43 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Sigma Cassiopeiae

Sigma Cassiopeiae has a spectral type of B1V.... This means the star is a blue main sequence dwarf star. The star has a B-V Colour Index of -0.07 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 10,845 Kelvin.

Sigma Cassiopeiae Radius has been calculated as being 13.08 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 9,098,353.04.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 38.77. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Sigma Cassiopeiae Apparent and Absolute Magnitudes

Sigma Cassiopeiae has an apparent magnitude of 4.88 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 -3.47 If you used the 2007 Parallax value, you would get an absolute magnitude of -5.83. 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 Sigma Cassiopeiae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.14 which gave the calculated distance to Sigma Cassiopeiae as 1524.13 light years away from Earth or 467.29 parsecs. It would take a spaceship travelling at the speed of light, 1524.13 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 0.72 which put Sigma Cassiopeiae at a distance of 4530.05 light years or 1388.89 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.

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.

Sigma Cassiopeiae Facts

Alternative Names

Flamsteed Name8 Cassiopeiae
Flamsteed Short Name8 Cas
Bayer DesignationSigma Cassiopeiae
Hipparcos Library I.D.118243
Bonner DurchmusterungBD+54 3082
Henry Draper Designation224572

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude-3.47 / -5.83
Visual / Apparent Magnitude4.88
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)23h 59m 00.53
Declination (Dec.)+55d45`17.8
Galactic Latitude-6.36 degrees
Galactic Longitude115.55 degrees
1997 Distance from Earth2.14 Parallax (milliarcseconds)
 1524.13 Light Years
 467.29 Parsecs
2007 Revised Distance from Earth0.72 Parallax (milliarcseconds)
 4530.05 Light Years
 1388.89 Parsecs
Proper Motion Dec.-5.01 ± 0.29 milliarcseconds/year
Proper Motion RA.8.14 ± 0.43 milliarcseconds/year
B-V Index-0.07
Radial Velocity-12.60 ± 2.80 km/s
Spectral TypeB1V...
Colour(B) blue

Estimated Facts

Calculated Effective Temperature10,845 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
224572+54 3082.0A5.000003.000009.00000B2Blue/White
B7.100001833
C1879

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