Universe Guide

W Persei

W Persei Facts

W Persei's Alternative Names

HIP13262 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD237008.

W Persei has alternative name(s) :- W Per, W Per.

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+56 724.

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

Location of W Persei

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 Persei, the location is 02h 50m 37.89 and +56° 59` 00.3 .

Radial Velocity and Proper Motion of W Persei

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 -3.32 ± 0.93 milliarcseconds/year towards the north and -0.48 ± 1.38 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 -39.00 km/s with an error of about 10.90 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 (Colour, Temperature) of W Persei

W Persei Colour and Temperature

W Persei has a spectral type of M3Iab. This means the star is a red supergiant star. The star has a B-V Colour Index of 2.5 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 18 Kelvin.

W Persei Apparent and Absolute Magnitudes

W Persei has an apparent magnitude of 8.91 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 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.37. 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 Persei

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -2.44 which gave the calculated distance to W Persei as -1336.74 light years away from Earth or -409.84 parsecs. It would take a spaceship travelling at the speed of light, -1336.74 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 0.35 which put W Persei at a distance of 9318.95 light years or 2857.14 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 589,323,322.06 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.

Variable Type of W Persei

The star is a pulsating Semiregular late- (M 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 Persei brightness ranges from a magnitude of 9.875 to a magnitude of 8.401 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 545.0 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 Persei Facts and Figures

Visual Facts

Primary / Proper / Traditional NameW Persei
Alternative NamesW Per, HD 237008, HIP 13262, BD+56 724, W Per
Spectral TypeM3Iab
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star Type very luminous Supergiant Star
GalaxyMilky Way
Absolute Magnitude / -3.37
Visual / Apparent Magnitude8.91
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)02h 50m 37.89
Declination (Dec.)+56° 59` 00.3
Galactic Latitude-2.20 degrees
Galactic Longitude138.65 degrees
1997 Distance from Earth-2.44 Parallax (milliarcseconds)
 -1336.74 Light Years
 -409.84 Parsecs
2007 Distance from Earth0.35 Parallax (milliarcseconds)
 9318.95 Light Years
 2857.14 Parsecs
 589,323,322.06 Astronomical Units
Proper Motion Dec.-3.32 ± 0.93 milliarcseconds/year
Proper Motion RA.-0.48 ± 1.38 milliarcseconds/year
B-V Index2.50
Radial Velocity-39.00 ± 10.90 km/s

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemiregular late- (M
Mean Variability Period in Days545.000
Variable Magnitude Range (Brighter - Dimmer)8.401 - 9.875

Estimated Calculated Facts

Effective Temperature18 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Comments and Questions

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