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4 Geminorum - HD42216 - HIP29288

4 Geminorum is a blue star that can be located in the constellation of Gemini. The star can not be seen by the naked eye, you need a telescope to see it.

HIP29288 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD42216.

4 Geminorum has alternative name(s), 4 Geminorum , 4 Gem. 4 Geminorum is a multiple star system with 2 stars orbiting in its solar system.

Location of 4 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 4 Geminorum, the location is 06h 10m 29.94 and +22d59`52.4 .

Proper Motion of 4 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 -2.15 ± 0.52 miliarcseconds/year towards the north and -4.58 ± 1.01 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 4 Geminorum

4 Geminorum has a spectral type of B9. This means the star is a blue star. The star has a B-V Colour Index of -0.07 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 12,523 Kelvin.

4 Geminorum Radius has been calculated as being 2.19 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,520,453.46.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.18. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

4 Geminorum Apparent and Absolute Magnitudes

4 Geminorum has an apparent magnitude of 6.88 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 -0.21 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.20. 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 4 Geminorum

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.82 which gave the calculated distance to 4 Geminorum as 853.83 light years away from Earth or 261.78 parsecs. It would take a spaceship travelling at the speed of light, 853.83 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 3.83 which put 4 Geminorum at a distance of 851.60 light years or 261.10 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.

4 Geminorum Facts

Alternative Names

Traditional/Proper Name4 Geminorum
Short Name4 Gem
Alternative Name(s)4 Geminorum
Hipparcos Library I.D.29288
Bonner DurchmusterungBDD+23 1232
Henry Draper Designation42216

Visual Facts

Star Type star
Absolute Magnitude-0.21 / -0.20
Visual / Apparent Magnitude6.88
Naked Eye VisibleRequires a 7x50 Binoculars - Ref: Wiki
Right Ascension (R.A.)06h 10m 29.94
Declination (Dec.)+22d59`52.4
Galactic Latitude1.87 degrees
Galactic Longitude187.94 degrees
1997 Distance from Earth3.82 Parallax (milliarcseconds)
 853.83 Light Years
 261.78 Parsecs
2007 Revised Distance from Earth3.83 Parallax (milliarcseconds)
 851.60 Light Years
 261.10 Parsecs
Proper Motion Dec.-2.15 ± 0.52 milliarcseconds/year
Proper Motion RA.-4.58 ± 1.01 milliarcseconds/year
B-V Index-0.07
Radial Velocity-8.90 ± 3.40 km/s
Spectral TypeB9
Colour(B) blue
Stars in Solar System2

Estimated Facts

Calculated Effective Temperature12,523 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
42216+23 1232.0A7.30000-2.000003.00000B9Blue/White
B7.600001960

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