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20 Ursae Minoris, HD147142, HIP79420

20 Ursae Minoris is a orange to red subgiant star that can be located in the constellation of UrsaMinor. 20 Ursae Minoris is the brightest star in Ursa Minor 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.

HIP79420 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD147142.

Location of 20 Ursae Minoris

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 20 Ursae Minoris, the location is 16h 12m 32.20 and +75d12`38.1 .

Proper Motion of 20 Ursae Minoris

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 35.15 ± 0.25 miliarcseconds/year towards the north and -43.57 ± 0.26 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 20 Ursae Minoris

20 Ursae Minoris has a spectral type of K2IV. This means the star is a orange to red subgiant star. The star is 7455.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24315.4772952000000000s. The star has a B-V Colour Index of 1.28 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,355 Kelvin.

20 Ursae Minoris Radius has been calculated as being 20.56 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 14,302,643.77.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 17.58. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

20 Ursae Minoris Apparent and Absolute Magnitudes

20 Ursae Minoris has an apparent magnitude of 6.36 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 -0.49 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.15. 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 20 Ursae Minoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.26 which gave the calculated distance to 20 Ursae Minoris as 765.64 light years away from Earth or 234.74 parsecs. It would take a spaceship travelling at the speed of light, 765.64 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 4.99 which put 20 Ursae Minoris at a distance of 653.63 light years or 200.40 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 7,455.00 Parsecs or 24,315.48 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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.

20 Ursae Minoris Facts

Alternative Names

Traditional/Proper Name20 Ursae Minoris
Flamsteed Name20 Ursae Minoris
Flamsteed Short Name20 UMi
Hipparcos Library I.D.79420
Bonner DurchmusterungBD+75 586
Henry Draper Designation147142

Visual Facts

Star Typesubgiant star
Absolute Magnitude-0.49 / -0.15
Visual / Apparent Magnitude6.36
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)16h 12m 32.20
Declination (Dec.)+75d12`38.1
Galactic Latitude35.88 degrees
Galactic Longitude108.91 degrees
1997 Distance from Earth4.26 Parallax (milliarcseconds)
 765.64 Light Years
 234.74 Parsecs
2007 Revised Distance from Earth4.99 Parallax (milliarcseconds)
 653.63 Light Years
 200.40 Parsecs
Galacto-Centric Distance24,315.48 Light Years / 7,455.00 Parsecs
Proper Motion Dec.35.15 ± 0.25 milliarcseconds/year
Proper Motion RA.-43.57 ± 0.26 milliarcseconds/year
B-V Index1.28
Radial Velocity-28.96 ± 0.20 km/s
Spectral TypeK2IV
Colour(K) Orange to Red

Estimated Facts

Calculated Effective Temperature4,355 Kelvin

Sources and Links

SIMBAD SourceLink

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