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AB Doradus, HD36705, HIP25647

AB Doradus is a orange to red rotating giant star that can be located in the constellation of Dorado. The star can not be seen by the naked eye, you need a telescope to see it.

AB Doradus's Alternative Names

HIP25647 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD36705.

AB Doradus has alternative name(s) :- , AB Dor.

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

Location of AB Doradus

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 AB Doradus, the location is 05h 28m 44.78 and -65° 26` 56.2 .

Proper Motion of AB Doradus

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 150.83 ± 0.60 miliarcseconds/year towards the north and 33.16 ± 0.57 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 32.40000 km/s with an error of about 2.20 km/s .

AB Doradus 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 0.4200000 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 AB Doradus

AB Doradus has a spectral type of K1III(p). This means the star is a orange to red giant star. The star is 7399.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24132.8258225600000000s. The star has a B-V Colour Index of 0.83 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,212 Kelvin.

AB Doradus Radius has been calculated as being 0.72 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 500,403.12.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 0.73. 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 -0.49 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

AB Doradus Apparent and Absolute Magnitudes

AB Doradus has an apparent magnitude of 6.88 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 6.01 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.98. 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 AB Doradus

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 66.92 which gave the calculated distance to AB Doradus as 48.74 light years away from Earth or 14.94 parsecs. It would take a spaceship travelling at the speed of light, 48.74 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 65.93 which put AB Doradus at a distance of 49.47 light years or 15.17 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 7,399.00 Parsecs or 24,132.83 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 AB Doradus

The star is a rotating FK Comae Berenices 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. AB Doradus brightness ranges from a magnitude of 7.125 to a magnitude of 6.989 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 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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AB Doradus Facts

Visual Facts

Alternative NamesHD 36705, HIP 25647, AB Dor
Star TypeGiant Star
GalaxyMilky Way
Absolute Magnitude6.01 / 5.98
Visual / Apparent Magnitude6.88
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)05h 28m 44.78
Declination (Dec.)-65° 26` 56.2
Galactic Latitude-33.05 degrees
Galactic Longitude275.30 degrees
1997 Distance from Earth66.92 Parallax (milliarcseconds)
 48.74 Light Years
 14.94 Parsecs
2007 Revised Distance from Earth65.93 Parallax (milliarcseconds)
 49.47 Light Years
 15.17 Parsecs
Galacto-Centric Distance24,132.83 Light Years / 7,399.00 Parsecs
Proper Motion Dec.150.83 ± 0.60 milliarcseconds/year
Proper Motion RA.33.16 ± 0.57 milliarcseconds/year
B-V Index0.83
Radial Velocity32.40 ± 2.20 km/s
Iron Abundance-0.49 ± 9.99 Fe/H
Semi-Major Axis6477.00
Stellar Luminosity (Lsun)0.42
Spectral TypeK1III(p)
Colour(K) Orange to Red

Variable Star Details

Variable Star ClassRotating
Variable Star TypeFK Comae Berenices
Mean Variability Period in Days0.112
Variable Magnitude Range (Brighter - Dimmer)6.989 - 7.125

Estimated Facts

Calculated Effective Temperature5,212 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
36705-65 475.4A6.8000048.00000132.00000G0Yellow

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