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Polaris B, Alpha Ursae Minoris B

Polaris B (Alpha Ursae Minoris B) is a blue to white main sequence dwarf star that can be located in the constellation of UrsaMinor. Polaris B is the brightest star in Ursa Minor based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.

Alpha Ursae Minoris B is the Bayer Classification for the star.

Polaris B 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 3.0000000 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, Radius) of Polaris B

Polaris B has a spectral type of F3V. This means the star is a blue to white main sequence dwarf star. Polaris B lies at a distance of 431.43 light years away from our Sun and our planet Earth or to put it another way, 132.27 parsecs away from the Sun.

Polaris B has been calculated as 1.38 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 960,204.00.km.

The star has a companion star which is in orbit close by, it has at least the following companions in close orbit, .

Polaris B Apparent and Absolute Magnitudes

Polaris B has an apparent magnitude of 8.70 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. 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 Polaris B

Polaris B is an estimated 431.43 light years from our Solar System (Earth and Sun). It would take a spaceship 431.43 years travelling at the speed of light to get there. We don't have a space ship that can travel that distance or at that speed yet.

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.

Polaris B Facts

Alternative Names

Traditional/Proper NamePolaris B
Bayer DesignationAlpha Ursae Minoris B

Visual Facts

Star Typemain sequence dwarf star
Visual / Apparent Magnitude8.70
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Declination (Dec.)+89 d 51 ` 38.1
Distance from the Sun / Earth431.43 Light Years
Spectral TypeF3V
Colour(F) blue to white

Estimated Facts

Radius (x the Sun)1.38
Luminosity (x the Sun)3.0000000

Related Stars

Location of Polaris B in Ursa Minor


Polaris B (Alpha Ursae Minoris B) Location in Ursa Minor

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


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