Universe Guide

23 Librae

23 Librae Facts

  • 23 Librae is a main sequence star that can be located in the constellation of Libra. The description is based on the spectral class.
  • 23 Librae is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (G5V) of the star, the star's colour is yellow .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • The star has an estimated age of 8.10 Billion of Years but could be as young as 5.40 to 9.70 according to Hipparcos.
  • 23 Librae has at least 2 Extrasolar Planets believed to be in orbit around the star.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 85.47 light years away from us. Distance

23 Librae's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR5657. HIP74500 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD134987. The Gliese ID of the star is GL 579.4. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 23 Librae. The Flamsteed name can be shortened to 23 Lib.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is CD-24 11928.

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

Location of 23 Librae

The location of the main sequence star in the night sky 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 object is compared to the celestial equator and is expressed in degrees. For 23 Librae, the location is 15h 13m 28.93 and -25° 18` 33.0 .

Radial Velocity and Proper Motion of 23 Librae

Proper Motion

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 -74.85 ± 0.37 milliarcseconds/year towards the north and -399.92 ± 0.60 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 5.18000 km/s with an error of about 0.08 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of 23 Librae

23 Librae Colour and Temperature

Based on the star's spectral type of G5V , 23 Librae's colour and type is yellow main sequence star. The star's effective temperature is 5,750 Kelvin which is cooler than our own Sun's effective Temperature which is 5,777 Kelvin

23 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 1.66 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

23 Librae Radius

23 Librae estimated radius has been calculated as being 1.30 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 903,440.41.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.3225602964390517348579180050. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

23 Librae Mass

The 23 Librae's solar mass is 1.07 times that of our star, the Sun. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

23 Librae Metalicity

The star's metallicity is 0.250000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.

23 Librae Estimated Age

The stars age according to Hipparcos data files put the star at an age of about 8.10 Billion years old but could be between 5.40 and 9.70 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

23 Librae Apparent and Absolute Magnitudes

23 Librae has an apparent magnitude of 6.47 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 4.42 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.38. 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 23 Librae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 38.98000 which gave the calculated distance to 23 Librae as 83.67 light years away from Earth or 25.65 parsecs. If you want that in miles, it is about 491,864,584,974,272.65, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 38.16000 which put 23 Librae at a distance of 85.47 light years or 26.21 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.

Using the 2007 distance, the star is roughly 5,406,162.90 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,378.00 Parsecs or 24,064.33 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to 23 Librae

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A38073677,877,178.37
Speed of Sound (Mach 1)767.26974,703,400.35
Concorde (Mach 2)1,534.5437,351,651.49
New Horizons Probe33,0001,736,897.07
Speed of Light670,616,629.0085.47

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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Additional 23 Librae Facts and Figures

Visual Facts

Primary / Proper / Traditional Name23 Librae
Alternative NamesHD 134987, HIP 74500, HR 5657, 23 Lib, CD-24 11928, Gliese 579.4
Spectral TypeG5V
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star Type Main Sequence Dwarf Star
GalaxyMilky Way
Age8.10 Billion Years Old
Age Range5.40 - 9.70 Billion Years Old
Absolute Magnitude 4.42 / 4.38
Visual / Apparent Magnitude6.47
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)15h 13m 28.93
Declination (Dec.)-25° 18` 33.0
Galactic Latitude27.38594952 degrees
Galactic Longitude339.18712166 degrees
1997 Distance from Earth38.98000 Parallax (milliarcseconds)
 83.67 Light Years
  25.65 Parsecs
2007 Distance from Earth38.16000 Parallax (milliarcseconds)
 85.47 Light Years
 26.21 Parsecs
 5,406,162.90 Astronomical Units
Galacto-Centric Distance24,064.33 Light Years / 7,378.00 Parsecs
Proper Motion Dec.-74.85000 ± 0.37000 milliarcseconds/year
Proper Motion RA.-399.92000 ± 0.60000 milliarcseconds/year
B-V Index0.69
Radial Velocity5.18000 ± 0.08 km/s
Iron Abundance0.2700 ± 0.01 Fe/H
Semi-Major Axis5907.0000000
Stellar Luminosity (Lsun)1.6600000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count2

Estimated Calculated Facts

Radius (x the Sun)1.32
Effective Temperature5,594 Kelvin
Mass Compared to the Sun1.07

Sources and Links

SIMBAD SourceLink

List of Extrasolar Planets orbiting 23 Librae

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
HD 134987 bConfirmed0.02258.1900.23319990.81252.700
HD 134987 cConfirmed0.035000.0000.1220095.8195.000

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