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Rho Cassiopeiae, 7 Cassiopeiae, HD224014, HIP117863

Rho Cassiopeiae is a blue to white pulsating very luminous supergiant star that can be located in the constellation of Cassiopeia. Rho 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.

Rho Cassiopeiae is the Bayer Classification for the star. HIP117863 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD224014.

Rho Cassiopeiae has alternative name(s), rho Cas.

Location of Rho 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 Rho Cassiopeiae, the location is 23h 54m 23.04 and +57d29`57.8 .

Proper Motion of Rho 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 -3.73 ± 0.15 miliarcseconds/year towards the north and -4.48 ± 0.21 miliarcseconds/year east if we saw them in the horizon.

Rho Cassiopeiae 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 12000.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

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

Rho Cassiopeiae has a spectral type of F8Iavar. This means the star is a blue to white supergiant star. The star has a B-V Colour Index of 1.19 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,586 Kelvin.

Rho Cassiopeiae Radius has been calculated as being 660.87 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 459,833,623.43.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 660.87. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is 0.05 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Rho Cassiopeiae Apparent and Absolute Magnitudes

Rho Cassiopeiae has an apparent magnitude of 4.51 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 -8.25 If you used the 2007 Parallax value, you would get an absolute magnitude of -8.25. 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 Rho Cassiopeiae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.28 which gave the calculated distance to Rho Cassiopeiae as 11648.69 light years away from Earth or 3571.43 parsecs. It would take a spaceship travelling at the speed of light, 11648.69 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 0.28 which put Rho Cassiopeiae at a distance of 11648.69 light years or 3571.43 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 Rho Cassiopeiae

The star is a pulsating Semiregular giants and supergiants of F, G, or K spectral s, sometimes with emission lines in their spectral 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. Rho Cassiopeiae brightness ranges from a magnitude of 4.755 to a magnitude of 4.574 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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.

Rho Cassiopeiae Facts

Alternative Names

Flamsteed Name7 Cassiopeiae
Flamsteed Short Name7 Cas
Short Namerho Cas
Bayer DesignationRho Cassiopeiae
Hipparcos Library I.D.117863
Bonner DurchmusterungBD+56 3111
Henry Draper Designation224014

Visual Facts

Star Typesupergiant star
Absolute Magnitude-8.25 / -8.25
Visual / Apparent Magnitude4.51
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)23h 54m 23.04
Declination (Dec.)+57d29`57.8
Galactic Latitude-4.52 degrees
Galactic Longitude115.30 degrees
1997 Distance from Earth0.28 Parallax (milliarcseconds)
 11648.69 Light Years
 3571.43 Parsecs
2007 Revised Distance from Earth0.28 Parallax (milliarcseconds)
 11648.69 Light Years
 3571.43 Parsecs
Proper Motion Dec.-3.73 ± 0.15 milliarcseconds/year
Proper Motion RA.-4.48 ± 0.21 milliarcseconds/year
B-V Index1.19
Radial Velocity-54.30 ± 0.40 km/s
Iron Abundance0.05 ± 9.99 Fe/H
Spectral TypeF8Iavar
Colour(F) blue to white

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemiregular giants and supergiants of F, G, or K spectral s, sometimes with emission lines in their spectral
Mean Variability Period in Days0.172
Variable Magnitude Range (Brighter - Dimmer)4.574 - 4.755

Estimated Facts

Luminosity (x the Sun)12,000.0000000
Calculated Effective Temperature4,586 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Rho Cassiopeiae in Cassiopeia


Rho Cassiopeiae (Rho Cassiopeiae) Location in Cassiopeia

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


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