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R Cassiopeiae, HD224490, HIP118188

R Cassiopeiae is a red pulsating variable star that can be located in the constellation of Cassiopeia. The star can not be seen by the naked eye, you need a telescope to see it.

R Cassiopeiae's Alternative Names

HIP118188 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD224490.

R Cassiopeiae has alternative name(s) :- , R Cas.

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+50 4202.

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

Location of R 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 R Cassiopeiae, the location is 23h 58m 24.79 and +51° 23` 19.5 .

Proper Motion of R 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 17.49 ± 0.72 miliarcseconds/year towards the north and 85.52 ± 1.02 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 -22.94000 km/s with an error of about 0.72 km/s .

R 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 3.8600000 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 R Cassiopeiae

R Cassiopeiae has a spectral type of M6:e.... This means the star is a red variable star. The star is 7451.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24302.4307614400000000s. The star has a B-V Colour Index of 1.5 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,014 Kelvin.

R Cassiopeiae Radius has been calculated as being 2.09 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,452,732.58.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.46. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

R Cassiopeiae Apparent and Absolute Magnitudes

R Cassiopeiae has an apparent magnitude of 9.97 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 4.83 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.47. 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 R Cassiopeiae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 9.37 which gave the calculated distance to R Cassiopeiae as 348.09 light years away from Earth or 106.72 parsecs. It would take a spaceship travelling at the speed of light, 348.09 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 7.95 which put R Cassiopeiae at a distance of 410.27 light years or 125.79 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 7,451.00 Parsecs or 24,302.43 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 R Cassiopeiae

The star is a pulsating Omicron Ceti 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. R Cassiopeiae brightness ranges from a magnitude of 9.293 to a magnitude of 5.053 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 431.3 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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R Cassiopeiae Facts

Visual Facts

Alternative NamesHD 224490, HIP 118188, BD+50 4202, R Cas
Star TypeVariable Star
GalaxyMilky Way
Absolute Magnitude4.83 / 4.47
Visual / Apparent Magnitude9.97
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)23h 58m 24.79
Declination (Dec.)+51° 23` 19.5
Galactic Latitude-10.62 degrees
Galactic Longitude114.56 degrees
1997 Distance from Earth9.37 Parallax (milliarcseconds)
 348.09 Light Years
 106.72 Parsecs
2007 Revised Distance from Earth7.95 Parallax (milliarcseconds)
 410.27 Light Years
 125.79 Parsecs
Galacto-Centric Distance24,302.43 Light Years / 7,451.00 Parsecs
Proper Motion Dec.17.49 ± 0.72 milliarcseconds/year
Proper Motion RA.85.52 ± 1.02 milliarcseconds/year
B-V Index1.50
Radial Velocity-22.94 ± 0.72 km/s
Semi-Major Axis5888.00
Stellar Luminosity (Lsun)3.86
Spectral TypeM6:e...
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeOmicron Ceti
Mean Variability Period in Days431.300
Variable Magnitude Range (Brighter - Dimmer)5.053 - 9.293

Estimated Facts

Calculated Effective Temperature4,014 Kelvin

Sources and Links

SIMBAD SourceLink

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
224490+50 4202.0A79.0000015.00000M4Red

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