Universe Guide


KU Librae - HD128987 - HIP71743

KU Librae is a white to yellow rotating main sequence dwarf star that can be located in the constellation of Libra. HIP71743 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD128987.

Location of KU Librae

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 KU Librae, the location is 14h 40m 31.17 and -16d12`32.9 .

Proper Motion of KU Librae

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 -064.97 ± 000.30 towards the north and -111.98 ± 000.54 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of KU Librae

KU Librae has a spectral type of G6V. This means the star is a white to yellow main sequence dwarf star. The star has a B-V Colour Index of 0.71 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,533 Kelvin.

KU Librae has been calculated as 0.85 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 593,490.36.km.

KU Librae Apparent and Absolute Magnitudes

KU Librae has an apparent magnitude of 7.24 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 5.38 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.37. 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 KU Librae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 42.43 which gave the calculated distance to KU Librae as 76.87 light years away from Earth or 23.57 parsecs. It would take a spaceship travelling at the speed of light, 76.87 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 42.23 which put KU Librae at a distance of 77.23 light years or 23.68 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 KU Librae

The star is a rotating BY Draconis 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.

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.

KU Librae Facts

Alternative Names

Traditional NameKU Librae
Hipparcos Library I.D.71743
Bonner DurchmusterungBD-15 3924
Henry Draper Designation128987

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude5.38 / 5.37
Apparent Magnitude7.24
Right Ascension (R.A.)14h 40m 31.17
Declination (Dec.)-16d12`32.9
1997 Distance from Earth42.43 Parallax (milliarcseconds)
 76.87 Light Years
 23.57 Parsecs
2007 Revised Distance from Earth42.23 Parallax (milliarcseconds)
 77.23 Light Years
 23.68 Parsecs
Proper Motion Dec.-64.97 ± 0.30 milliarcseconds/year
Proper Motion RA.-111.98 ± 0.54 milliarcseconds/year
B-V Index0.71
Spectral TypeG6V
Colour(G) White to Yellow

Variable Star Details

Variable Star ClassRotating
Variable Star TypeBY Draconis

Estimated Facts

Radius (x the Sun)0.85
Calculated Effective Temperature5,533 Kelvin

Sources and Links

SIMBAD SourceLink

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