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Mekbuda, Zeta Geminorum, 43 Geminorum, HD52973, HIP34088, HR2650

Mekbuda (Zeta Geminorum) is a white to yellow pulsating very luminous supergiant star that can be located in the constellation of Gemini. Mekbuda is the brightest star in Gemini 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.

Zeta Geminorum is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR2650. HIP34088 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD52973.

Mekbuda has alternative name(s), zet Gem.

Location of Mekbuda

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 Mekbuda, the location is 07h 04m 06.54 and +20d34`13.1 .

Proper Motion of Mekbuda

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 -0.41 ± 0.20 miliarcseconds/year towards the north and -7.29 ± 0.30 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Mekbuda

Mekbuda has a spectral type of G3Ibv SB. This means the star is a white to yellow supergiant star. The star is 7791.00000000 Parsecs from the Galactic Centre or terms of Light Years is 25411.3861310400000000s. The star has a B-V Colour Index of 0.89 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,217 Kelvin.

Mekbuda Radius has been calculated as being 64.58 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 44,934,826.66.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 76.23. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is 0.11 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Mekbuda Apparent and Absolute Magnitudes

Mekbuda has an apparent magnitude of 4.01 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 -3.76 If you used the 2007 Parallax value, you would get an absolute magnitude of -4.12. 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 Mekbuda

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.79 which gave the calculated distance to Mekbuda as 1169.04 light years away from Earth or 358.42 parsecs. It would take a spaceship travelling at the speed of light, 1169.04 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 2.37 which put Mekbuda at a distance of 1376.22 light years or 421.94 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 7,791.00 Parsecs or 25,411.39 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of Mekbuda

The star is a pulsating Delta Cepheid 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. Mekbuda brightness ranges from a magnitude of 4.328 to a magnitude of 3.782 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 10.2 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.

Mekbuda Facts

Alternative Names

Traditional/Proper NameMekbuda
Flamsteed Name43 Geminorum
Flamsteed Short Name43 Gem
Short Namezet Gem
Bayer DesignationZeta Geminorum
Hipparcos Library I.D.34088
Yale Bright Star Catalogue (HR) Id2650
Bonner DurchmusterungBD+20 1687
Henry Draper Designation52973

Visual Facts

Star Typesupergiant star
Absolute Magnitude-3.76 / -4.12
Visual / Apparent Magnitude4.01
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)07h 04m 06.54
Declination (Dec.)+20d34`13.1
Galactic Latitude11.90 degrees
Galactic Longitude195.75 degrees
1997 Distance from Earth2.79 Parallax (milliarcseconds)
 1169.04 Light Years
 358.42 Parsecs
2007 Revised Distance from Earth2.37 Parallax (milliarcseconds)
 1376.22 Light Years
 421.94 Parsecs
Galacto-Centric Distance25,411.39 Light Years / 7,791.00 Parsecs
Proper Motion Dec.-0.41 ± 0.20 milliarcseconds/year
Proper Motion RA.-7.29 ± 0.30 milliarcseconds/year
B-V Index0.89
Radial Velocity2.80 ± 0.20 km/s
Iron Abundance0.11 ± 9.99 Fe/H
Spectral TypeG3Ibv SB
Colour(G) White to Yellow

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeDelta Cepheid
Mean Variability Period in Days10.151
Variable Magnitude Range (Brighter - Dimmer)3.782 - 4.328

Estimated Facts

Calculated Effective Temperature5,217 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.


Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
52973+20 1687.0A-8.00000-3.00000G0Yellow
B10.500001880
268518+20 1686.0C8.00000-88.0000045.00000GYellow1925
P12.000001905
CR12.900001907

Location of Mekbuda in Gemini


Mekbuda (Zeta Geminorum) Location in Gemini

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


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