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Omicron Librae - HD136407 - HIP75118

Omicron Librae is a blue to white main sequence dwarf star that can be located in the constellation of Libra. Omicron Librae is the Bayer Classification for the star. HIP75118 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD136407. Omicron Librae has alternative name(s), 29 Librae , 29 Lib.

Location of Omicron 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 Omicron Librae, the location is 15h 21m 01.36 and -15d32`54.2 .

Proper Motion of Omicron 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 018.35 ± 000.73 towards the north and 027.86 ± 000.94 east if we saw them in the horizon.

Omicron Librae 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 4.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

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

Omicron Librae has a spectral type of F2V. This means the star is a blue to white main sequence dwarf star. The star has a B-V Colour Index of 0.39 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,775 Kelvin.

Omicron Librae has been calculated as 2.19 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,525,967.13.km.

Omicron Librae Apparent and Absolute Magnitudes

Omicron Librae has an apparent magnitude of 6.14 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 2.45 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.37. 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 Omicron Librae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 18.31 which gave the calculated distance to Omicron Librae as 178.13 light years away from Earth or 54.61 parsecs. It would take a spaceship travelling at the speed of light, 178.13 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 17.65 which put Omicron Librae at a distance of 184.80 light years or 56.66 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.

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.

Omicron Librae Facts

Alternative Names

Short Name29 Lib
Bayer DesignationOmicron Librae
Alternative Name(s)29 Librae
Hipparcos Library I.D.75118
Bonner DurchmusterungBD-15 4083
Henry Draper Designation136407

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude2.45 / 2.37
Apparent Magnitude6.14
Right Ascension (R.A.)15h 21m 01.36
Declination (Dec.)-15d32`54.2
1997 Distance from Earth18.31 Parallax (milliarcseconds)
 178.13 Light Years
 54.61 Parsecs
2007 Revised Distance from Earth17.65 Parallax (milliarcseconds)
 184.80 Light Years
 56.66 Parsecs
Proper Motion Dec.18.35 ± 0.73 milliarcseconds/year
Proper Motion RA.27.86 ± 0.94 milliarcseconds/year
B-V Index0.39
Spectral TypeF2V
Colour(F) blue to white

Estimated Facts

Radius (x the Sun)2.19
Luminosity (x the Sun)4.0000000
Calculated Effective Temperature6,775 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
136407-15 4083.0A6.2000023.0000022.00000F5Yellow/White
B8.400009.00000-37.000001960

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