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Menkent, Theta Centauri, HD123139, HIP68933, HR5288

Menkent (Theta Centauri) is a orange to red giant star that can be located in the constellation of Centaurus. The description is based on the spectral class. Menkent is the 53rd brightest star in the night sky and the 4th brightest star in Centaurus 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.

Menkent's Alternative Names

Theta Centauri (The Cen) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR5288. HIP68933 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD123139. The Gliese ID of the star is GL 539. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Ref : Star Names.

Menkent has alternative name(s) :- Theta CenTau .

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 314 G. Centauri. There are no stars with a Gould designation in Ursa Major for example.

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

Location of Menkent

The location of the 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 star is compared to the celestial equator and is expressed in degrees. For Menkent, the location is 14h 06m 41.32 and -36° 22` 07.3 .

Proper Motion of Menkent

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 -518.06 ± 0.11 miliarcseconds/year towards the north and -520.53 ± 0.20 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is 1.30000 km/s with an error of about 0.50 km/s .

Menkent 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 59.84 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of Menkent

Menkent has a spectral type of K0IIIb. This means the star is a orange to red giant star. The star is 7,387.00 Parsecs from the Galactic Centre or terms of Light Years is 24,093.69 s. The star has a B-V Colour Index of 1.01 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,830 Kelvin.

Menkent Radius has been calculated as being 9.66 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 6,721,817.18.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 9.31. 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 0.08 with an error value of 0.06 Fe/H with the Sun has a value of 1 to put it into context.

Menkent Apparent and Absolute Magnitudes

Menkent has an apparent magnitude of 2.06 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 0.70 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.78. 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 Menkent

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 53.52 which gave the calculated distance to Menkent as 60.94 light years away from Earth or 18.68 parsecs. It would take a spaceship travelling at the speed of light, 60.94 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 55.45 which put Menkent at a distance of 58.82 light years or 18.03 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 7,387.00 Parsecs or 24,093.69 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Meteor Showers Radiating from near Menkent

The Theta Centaurids Meteor Shower radiants from a point near this star. The meteor shower runs typically between Feb 12 - Feb 16 with a peak date of Feb 14. The speed of a meteor in the shower is 59 Km/s. The amount of meteors predicted to be seen per hour (Zenith Hourly Rate) is 59.

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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Menkent Facts

Visual Facts


 Menkent
Alternative NamesTheta Centauri, The Cen, Theta CenTau, HD 123139, HIP 68933, HR 5288, 314 G. Centauri, Gliese 539
Spectral TypeK0IIIb
Multiple Star SystemYes
Star TypeGiant Star
Colour orange to red
GalaxyMilky Way
ConstellationCentaurus
Absolute Magnitude0.70 / 0.78
Visual / Apparent Magnitude2.06
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)14h 06m 41.32
Declination (Dec.)-36° 22` 07.3
Galactic Latitude24.08 degrees
Galactic Longitude319.46 degrees
1997 Distance from Earth53.52 Parallax (milliarcseconds)
 60.94 Light Years
 18.68 Parsecs
2007 Distance from Earth55.45 Parallax (milliarcseconds)
 58.82 Light Years
 18.03 Parsecs
Galacto-Centric Distance24,093.69 Light Years / 7,387.00 Parsecs
Proper Motion Dec.-518.06 ± 0.11 milliarcseconds/year
Proper Motion RA.-520.53 ± 0.20 milliarcseconds/year
B-V Index1.01
Radial Velocity1.30 ± 0.50 km/s
Iron Abundance0.08 ± 0.06 Fe/H
Eccentricity0.31
Semi-Major Axis5376.00
Stellar Luminosity (Lsun)59.84
Brightest in Night Sky53rd

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Facts


Calculated Effective Temperature4,830 Kelvin

Sources and Links


SIMBAD SourceLink

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
123139-35 9260.2A2.30000-521.00000-523.00000K0Orange
B14.300001897

Location of Menkent in Centaurus


Menkent (Theta Centauri) Location in Centaurus

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

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