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AB Crucis - HD106871 - HIP59935

AB Crucis is a blue eclipsing binary system subgiant star that can be located in the constellation of Crux. HIP59935 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD106871. AB Crucis has alternative name(s), AB_Cru.

Location of AB Crucis

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 Crucis, the location is 12h 17m 37.14 and -58d09`52.4 .

Proper Motion of AB Crucis

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 0.52 ± 0.55 miliarcseconds/year towards the north and -11.27 ± 0.88 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of AB Crucis

AB Crucis has a spectral type of B0IVvar. This means the star is a blue subgiant star. The star has a B-V Colour Index of 0.09 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 8,538 Kelvin.

AB Crucis has been calculated as 20.81 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 14,478,024.31.km.

AB Crucis Apparent and Absolute Magnitudes

AB Crucis has an apparent magnitude of 8.44 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 -3.44 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.43. 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 Crucis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.42 which gave the calculated distance to AB Crucis as 7765.79 light years away from Earth or 2380.95 parsecs. It would take a spaceship travelling at the speed of light, 7765.79 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 1.68 which put AB Crucis at a distance of 1941.45 light years or 595.24 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.

Variable Type of AB Crucis

The star is a eclipsing binary system Beta Lyrae (Sheliak) 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 Crucis brightness ranges from a magnitude of 9.000 to a magnitude of 8.000 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 3.0 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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

AB Crucis Facts

Alternative Names

Traditional/Proper NameAB Crucis
Short NameAB Cru
Hipparcos Library I.D.59935
Henry Draper Designation106871

Visual Facts

Star Typesubgiant star
Absolute Magnitude-3.44 / -0.43
Apparent Magnitude8.44
Right Ascension (R.A.)12h 17m 37.14
Declination (Dec.)-58d09`52.4
1997 Distance from Earth0.42 Parallax (milliarcseconds)
 7765.79 Light Years
 2380.95 Parsecs
2007 Revised Distance from Earth1.68 Parallax (milliarcseconds)
 1941.45 Light Years
 595.24 Parsecs
Proper Motion Dec.0.52 ± 0.55 milliarcseconds/year
Proper Motion RA.-11.27 ± 0.88 milliarcseconds/year
B-V Index0.09
Spectral TypeB0IVvar
Colour(B) blue

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeBeta Lyrae (Sheliak)
Mean Variability Period in Days3.000
Variable Magnitude Range (Brighter - Dimmer)8.000 - 9.000

Estimated Facts

Radius (x the Sun)20.81
Calculated Effective Temperature8,538 Kelvin

Sources and Links

SIMBAD SourceLink

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