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30 Librae - HD136801 - HIP75294

30 Librae is a orange to red giant star that can be located in the constellation of Libra. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

HIP75294 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD136801.

30 Librae has alternative name(s), 30 Librae , 30 Lib.

Location of 30 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 30 Librae, the location is 15h 23m 01.78 and -15d08`02.7 .

Proper Motion of 30 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 14.73 ± 0.53 miliarcseconds/year towards the north and 2.86 ± 0.77 miliarcseconds/year east if we saw them in the horizon.

30 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 45.0000000 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 30 Librae

30 Librae has a spectral type of K4III. This means the star is a orange to red giant star. The star has a B-V Colour Index of 1.6 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,779 Kelvin.

30 Librae Radius has been calculated as being 26.56 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 18,477,289.70.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 32.97. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

30 Librae Apparent and Absolute Magnitudes

30 Librae has an apparent magnitude of 6.46 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 -0.43 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.90. 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 30 Librae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.18 which gave the calculated distance to 30 Librae as 780.30 light years away from Earth or 239.23 parsecs. It would take a spaceship travelling at the speed of light, 780.30 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 3.37 which put 30 Librae at a distance of 967.84 light years or 296.74 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 Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

30 Librae Facts

Alternative Names

Traditional/Proper Name30 Librae
Short Name30 Lib
Alternative Name(s)30 Librae
Hipparcos Library I.D.75294
Bonner DurchmusterungBDD-14 4188
Henry Draper Designation136801

Visual Facts

Star Typegiant star
Absolute Magnitude-0.43 / -0.90
Visual / Apparent Magnitude6.46
Naked Eye VisibleYes - Ref: Wiki
Right Ascension (R.A.)15h 23m 01.78
Declination (Dec.)-15d08`02.7
Galactic Latitude33.98 degrees
Galactic Longitude348.58 degrees
1997 Distance from Earth4.18 Parallax (milliarcseconds)
 780.30 Light Years
 239.23 Parsecs
2007 Revised Distance from Earth3.37 Parallax (milliarcseconds)
 967.84 Light Years
 296.74 Parsecs
Proper Motion Dec.14.73 ± 0.53 milliarcseconds/year
Proper Motion RA.2.86 ± 0.77 milliarcseconds/year
B-V Index1.60
Radial Velocity13.70 ± 2.90 km/s
Spectral TypeK4III
Colour(K) Orange to Red

Estimated Facts

Luminosity (x the Sun)45.0000000
Calculated Effective Temperature3,779 Kelvin

Sources and Links

SIMBAD SourceLink

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