Universe Guide

HomeFactsConstellationsGemini

20 Geminorum - HD46136 - HIP31158

20 Geminorum is a blue to white main sequence dwarf star that can be located in the constellation of Gemini. 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 2.30 Billion of Years but could be as young as 2.00 to 2.60 according to Hipparcos.

HIP31158 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD46136.

20 Geminorum has alternative name(s), 20 Geminorum , 20 Gem. 20 Geminorum is a multiple star system with 2 stars orbiting in its solar system.

Location of 20 Geminorum

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 20 Geminorum, the location is 06h 32m 18.52 and +17d47`03.4 .

Proper Motion of 20 Geminorum

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 22.89 ± 3.52 miliarcseconds/year towards the north and 50.09 ± 4.64 miliarcseconds/year east if we saw them in the horizon.

20 Geminorum 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 2.0000000 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, Age, Radius) of 20 Geminorum

20 Geminorum has a spectral type of F6V.... This means the star is a blue to white main sequence dwarf star. The star has a B-V Colour Index of 0.54 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,122 Kelvin.

20 Geminorum Radius has been calculated as being 5.05 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,512,291.69.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 3.72. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is 0.10 with an error value of 0.08 Fe/H with the Sun has a value of 1 to put it into context.

The stars age according to Hipparcos data files put the star at an age of about 2.30 Billion years old but could be between 2.00 and 2.60 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

20 Geminorum Apparent and Absolute Magnitudes

20 Geminorum has an apparent magnitude of 6.26 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 1.08 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.74. 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 20 Geminorum

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 9.21 which gave the calculated distance to 20 Geminorum as 354.14 light years away from Earth or 108.58 parsecs. It would take a spaceship travelling at the speed of light, 354.14 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 12.46 which put 20 Geminorum at a distance of 261.77 light years or 80.26 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.

20 Geminorum Facts

Alternative Names

Traditional/Proper Name20 Geminorum
Short Name20 Gem
Alternative Name(s)20 Geminorum
Hipparcos Library I.D.31158
Bonner DurchmusterungBDD+17 1286
Henry Draper Designation46136

Visual Facts

Star Typemain sequence dwarf star
Age2.30 Billion Years Old
Age Range2.00 - 2.60 Billion Years Old
Absolute Magnitude1.08 / 1.74
Visual / Apparent Magnitude6.26
Naked Eye VisibleYes - Ref: Wiki
Right Ascension (R.A.)06h 32m 18.52
Declination (Dec.)+17d47`03.4
Galactic Latitude3.93 degrees
Galactic Longitude194.95 degrees
1997 Distance from Earth9.21 Parallax (milliarcseconds)
 354.14 Light Years
 108.58 Parsecs
2007 Revised Distance from Earth12.46 Parallax (milliarcseconds)
 261.77 Light Years
 80.26 Parsecs
Proper Motion Dec.22.89 ± 3.52 milliarcseconds/year
Proper Motion RA.50.09 ± 4.64 milliarcseconds/year
B-V Index0.54
Radial Velocity1.50 ± 0.40 km/s
Iron Abundance0.10 ± 0.08 Fe/H
Spectral TypeF6V...
Colour(F) blue to white
Stars in Solar System2

Estimated Facts

Luminosity (x the Sun)2.0000000
Calculated Effective Temperature6,122 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars


Add a Comment


Name:
Email: (Optional)
Comment: