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HD 120084, HIP66903

HD 120084 is a white to yellow giant star that can be located in the constellation of UrsaMinor. HD 120084 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.

HIP66903 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD120084. HD 120084 has at least 1 Extrasolar Planets believed to be in orbit around the star.

Location of HD 120084

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 HD 120084, the location is 13h 42m 39.38 and +78d03`51.6 .

Proper Motion of HD 120084

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 45.97 ± 0.23 miliarcseconds/year towards the north and -64.60 ± 0.24 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Metallicity, Mass, Radius) of HD 120084

HD 120084 has a spectral type of G7III:. This means the star is a white to yellow giant star. The star is 7439.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24263.2911601600000000s. The star has a B-V Colour Index of 1 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,849 Kelvin.

HD 120084 Radius has been calculated as being 8.50 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 5,916,624.90.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 8.78. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's solar mass is 2.39 times that of the Sun's. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

The star's metallicity is 0.090000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.

HD 120084 Apparent and Absolute Magnitudes

HD 120084 has an apparent magnitude of 5.91 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 0.96 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.89. 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 HD 120084

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 10.24 which gave the calculated distance to HD 120084 as 318.52 light years away from Earth or 97.66 parsecs. It would take a spaceship travelling at the speed of light, 318.52 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 9.93 which put HD 120084 at a distance of 328.46 light years or 100.70 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 7,439.00 Parsecs or 24,263.29 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.

HD 120084 Facts

Alternative Names

Traditional/Proper NameHD 120084
Hipparcos Library I.D.66903
Bonner DurchmusterungBD+78 466
Henry Draper Designation120084

Visual Facts

Star Typegiant star
Metalicity0.0900
Absolute Magnitude0.96 / 0.89
Visual / Apparent Magnitude5.91
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)13h 42m 39.38
Declination (Dec.)+78d03`51.6
Galactic Latitude38.73 degrees
Galactic Longitude119.56 degrees
1997 Distance from Earth10.24 Parallax (milliarcseconds)
 318.52 Light Years
 97.66 Parsecs
2007 Revised Distance from Earth9.93 Parallax (milliarcseconds)
 328.46 Light Years
 100.70 Parsecs
Galacto-Centric Distance24,263.29 Light Years / 7,439.00 Parsecs
Proper Motion Dec.45.97 ± 0.23 milliarcseconds/year
Proper Motion RA.-64.60 ± 0.24 milliarcseconds/year
B-V Index1.00
Radial Velocity-8.84 ± 0.28 km/s
Iron Abundance0.10 ± 0.02 Fe/H
Spectral TypeG7III:
Colour(G) White to Yellow

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Facts

Calculated Effective Temperature4,849 Kelvin
Mass Compared to the Sun2.39
Metallicity0.09000

Sources and Links

SIMBAD SourceLink

Related Stars


List of Extrasolar Planets orbiting HD 120084


NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
Hd 120084 BConfirmed4.52082.0000.6620134.3117.000

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