Universe Guide

GK Ursae Majoris

GK Ursae Majoris Facts

  • GK Ursae Majoris is a giant star that can be located in the constellation of Ursa Major. The description is based on the spectral class.
  • GK Ursae Majoris is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (M2III:) of the star, the star's colour is 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 2836.20 light years away from us. Distance

GK Ursae Majoris's Alternative Names

HIP47364 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD83205.

GK Ursae Majoris has alternative name(s) :- GK UMa, GK UMa.

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+59 1249.

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

Location of GK Ursae Majoris

The location of the giant 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 GK Ursae Majoris, the location is 09h 39m 00.74 and +58° 32` 53.4 .

Radial Velocity and Proper Motion of GK Ursae Majoris

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 1.44 ± 0.39 milliarcseconds/year towards the north and -13.01 ± 0.75 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 21.68000 km/s with an error of about 0.23 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 GK Ursae Majoris

GK Ursae Majoris Temperature and Colour

Based on the star's spectral type of M2III: , GK Ursae Majoris's colour and type is red giant star. The star has a B-V Colour Index of 1.64 which means the star's temperature is about 3,671 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

GK Ursae Majoris Radius

GK Ursae Majoris estimated radius has been calculated as being 125.71 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 87,469,207.11.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 69.080902468488633940196625646. 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.

GK Ursae Majoris Apparent and Absolute Magnitudes

GK Ursae Majoris has an apparent magnitude of 7.32 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 -3.68 If you used the 2007 Parallax value, you would get an absolute magnitude of -2.38. 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 GK Ursae Majoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.63000 which gave the calculated distance to GK Ursae Majoris as 5177.20 light years away from Earth or 1587.30 parsecs. If you want that in miles, it is about 30,434,819,282,046,185.69, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 1.15000 which put GK Ursae Majoris at a distance of 2836.20 light years or 869.57 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 179,360,437.77 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 GK Ursae Majoris

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 A3807362,584,243,047.79
Speed of Sound (Mach 1)767.2692,478,925,752.47
Concorde (Mach 2)1,534.541,239,461,260.81
New Horizons Probe33,00057,636,451.01
Speed of Light670,616,629.002,836.20
GK Ursae Majoris brightness ranges from a magnitude of 7.423 to a magnitude of 7.359 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 369.0 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 GK Ursae Majoris Facts and Figures

Visual Facts

Primary / Proper / Traditional NameGK Ursae Majoris
Alternative NamesGK UMa, HD 83205, HIP 47364, BD+59 1249, GK UMa
Spectral TypeM2III:
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeGiant Star
GalaxyMilky Way
ConstellationUrsa Major
Absolute Magnitude -3.68 / -2.38
Visual / Apparent Magnitude7.32
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)09h 39m 00.74
Declination (Dec.)+58° 32` 53.4
Galactic Latitude44.35318003 degrees
Galactic Longitude155.83316984 degrees
1997 Distance from Earth0.63000 Parallax (milliarcseconds)
 5177.20 Light Years
 1587.30 Parsecs
2007 Distance from Earth1.15000 Parallax (milliarcseconds)
 2836.20 Light Years
 869.57 Parsecs
 179,360,437.77 Astronomical Units
Proper Motion Dec.1.44000 ± 0.39000 milliarcseconds/year
Proper Motion RA.-13.01000 ± 0.75000 milliarcseconds/year
B-V Index1.64
Radial Velocity21.68000 ± 0.23 km/s

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Mean Variability Period in Days369.000
Variable Magnitude Range (Brighter - Dimmer)7.359 - 7.423

Estimated Calculated Facts

Radius (x the Sun)69.08
Effective Temperature3,671 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Comments and Questions

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