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Hadar, Beta Centauri, HD122451, HIP68702, HR5267

Hadar (Beta Centauri) is a blue pulsating star that can be located in the constellation of Centaurus. Hadar is the 12th brightest star in the night sky and the 2nd 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.

Beta Centauri is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR5267. HIP68702 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD122451. The Id of the star in the Gould Star Catalogue is 304. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major.

Hadar has alternative name(s), Beta CenTau, Agena , bet Cen. In Arabic, it is known as Hadar.

Location of Hadar

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 Hadar, the location is 14h 03m 49.44 and -60d 22` 22.7 .

Proper Motion of Hadar

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 -23.16 ± 0.34 miliarcseconds/year towards the north and -33.27 ± 0.50 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 5.90000 km/s with an error of about 3.80 km/s .

Physical Properties (Colour, Temperature, Radius) of Hadar

Hadar has a spectral type of B1III. This means the star is a blue star. The star is 7321.00000000 Parsecs from the Galactic Centre or terms of Light Years is 23878.4184142400000000s. The star has a B-V Colour Index of -0.23 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 19,982 Kelvin.

Hadar Radius has been calculated as being 9.46 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 6,579,049.17.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 7.07. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Hadar Apparent and Absolute Magnitudes

Hadar has an apparent magnitude of 0.61 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 -5.42 If you used the 2007 Parallax value, you would get an absolute magnitude of -4.79. 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 Hadar

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 6.21 which gave the calculated distance to Hadar as 525.22 light years away from Earth or 161.03 parsecs. It would take a spaceship travelling at the speed of light, 525.22 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 8.32 which put Hadar at a distance of 392.02 light years or 120.19 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 7,321.00 Parsecs or 23,878.42 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 Hadar

The star is a pulsating Beta Cephei 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. Hadar brightness ranges from a magnitude of 0.556 to a magnitude of 0.516 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.0 days (variability).

Meteor Showers Radiating from near Hadar

The Beta Centaurids Meteor Shower radiants from a point near this star. The meteor shower runs typically between 2-Feb - 25 Feb with a peak date of Feb 8/9.

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.

Hadar Facts

Alternative Names

Traditional/Proper NameHadar
Short Namebet Cen
Arabic NameHadar
English MeaningUn-translated
Bayer DesignationBeta Centauri
Alternative Name(s)Beta CenTau, Agena
Hipparcos Library I.D.68702
Yale Bright Star Catalogue (HR) Id5267
Gould I.D.304
Henry Draper Designation122451

Visual Facts

Star Type star
Absolute Magnitude-5.42 / -4.79
Visual / Apparent Magnitude0.61
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)14h 03m 49.44
Declination (Dec.)-60d 22` 22.7
Galactic Latitude1.25 degrees
Galactic Longitude311.77 degrees
1997 Distance from Earth6.21 Parallax (milliarcseconds)
 525.22 Light Years
 161.03 Parsecs
2007 Revised Distance from Earth8.32 Parallax (milliarcseconds)
 392.02 Light Years
 120.19 Parsecs
Galacto-Centric Distance23,878.42 Light Years / 7,321.00 Parsecs
Proper Motion Dec.-23.16 ± 0.34 milliarcseconds/year
Proper Motion RA.-33.27 ± 0.50 milliarcseconds/year
B-V Index-0.23
Radial Velocity5.90 ± 3.80 km/s
Spectral TypeB1III
Brightest in Night Sky12th
Colour(B) blue

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeBeta Cephei
Mean Variability Period in Days0.030
Variable Magnitude Range (Brighter - Dimmer)0.516 - 0.556

Estimated Facts

Calculated Effective Temperature19,982 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
122451-59 5365.4A0.90000-21.00000-23.00000B3Blue/White

Location of Hadar in Centaurus

Hadar (Beta Centauri) Location in Centaurus

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

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