Universe Guide

W Cephei

W Cephei Facts

  • W Cephei is a pulsating supergiant star that can be located in the constellation of Cepheus. The description is based on the spectral class.
  • W Cephei is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K0Iapev SB) of the star, the star's colour is orange to red .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 163081.67 light years away from us. Distance

W Cephei's Alternative Names

HIP111592 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD214369.

W Cephei has alternative name(s) :- , W 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+57 2568.

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

Location of W Cephei

The location of the supergiant 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 object is compared to the celestial equator and is expressed in degrees. For W Cephei, the location is 22h 36m 27.57 and +58° 25` 34.0 .

Radial Velocity and Proper Motion of W Cephei

Proper Motion

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 -3.27 ± 0.45 milliarcseconds/year towards the north and -2.48 ± 0.59 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -44.64000 km/s with an error of about 0.70 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of W Cephei

W Cephei Colour and Temperature

Based on the star's spectral type of K0Iapev SB , W Cephei's colour and type is orange to red supergiant star. The star has a B-V Colour Index of 1.79 which means the star's temperature is about 3,073 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

W Cephei Radius

W Cephei estimated radius has been calculated as being 137.98 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 96,004,865.22.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 5033.6787196562382229597546019. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

W Cephei Apparent and Absolute Magnitudes

W Cephei has an apparent magnitude of 7.57 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 -3.11 If you used the 2007 Parallax value, you would get an absolute magnitude of -10.92. 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 W Cephei

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.73000 which gave the calculated distance to W Cephei as 4467.99 light years away from Earth or 1369.86 parsecs. If you want that in miles, it is about 26,265,639,381,130,637.64, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 0.02000 which put W Cephei at a distance of 163081.67 light years or 50000 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.

Using the 2007 distance, the star is roughly 10,313,168,449.20 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

Travel Time to W Cephei

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A380736148,594,130,145.50
Speed of Sound (Mach 1)767.269142,538,379,352.08
Concorde (Mach 2)1,534.5471,269,096,789.32
New Horizons Probe33,0003,314,099,387.49
Speed of Light670,616,629.00163,081.67

Variable Type of W Cephei

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. W Cephei brightness ranges from a magnitude of 7.965 to a magnitude of 7.327 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.7 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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Additional W Cephei Facts and Figures

Visual Facts

Primary / Proper / Traditional NameW Cephei
Alternative NamesHD 214369, HIP 111592, BD+57 2568, W Cep
Spectral TypeK0Iapev SB
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star Type very luminous Supergiant Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude -3.11 / -10.92
Visual / Apparent Magnitude7.57
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)22h 36m 27.57
Declination (Dec.)+58° 25` 34.0
Galactic Latitude0.05711344 degrees
Galactic Longitude106.02279221 degrees
1997 Distance from Earth0.73000 Parallax (milliarcseconds)
 4467.99 Light Years
 1369.86 Parsecs
2007 Distance from Earth0.02000 Parallax (milliarcseconds)
 163081.67 Light Years
 50000 Parsecs
 10,313,168,449.20 Astronomical Units
Proper Motion Dec.-3.27000 ± 0.45000 milliarcseconds/year
Proper Motion RA.-2.48000 ± 0.59000 milliarcseconds/year
B-V Index1.79
Radial Velocity-44.64000 ± 0.70 km/s

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.652
Variable Magnitude Range (Brighter - Dimmer)7.327 - 7.965

Estimated Calculated Facts

Radius (x the Sun)5,033.68
Effective Temperature3,073 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Comments and Questions

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