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Tegmen (Zeta Cancri) - HD68255 - HIP40167 - HR3208

Tegmen (Zeta Cancri) is a white to yellow main sequence dwarf star that can be located in the constellation of Cancer. 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 2.20 to 2.40 according to Hipparcos.

Zeta Cancri is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR3208. HIP40167 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD68255.

Tegmen has alternative name(s), Tegmine,16 Cancri , 16 Cnc. Tegmen is a multiple star system with 4 stars orbiting in its solar system.

Tegmen is a multiple star system that has at least four stars in two binary pairs. However only one of these stars is catalogued on this site. Tegmen/Tegmine refers to the primary star in the system, Zeta Cancri A. Wikipedia

Location of Tegmen

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 Tegmen, the location is 08h 12m 12.71 and +17d38`53.3 .

Proper Motion of Tegmen

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 -151.73 ± 0.82 miliarcseconds/year towards the north and 27.61 ± 0.82 miliarcseconds/year east if we saw them in the horizon.

Tegmen 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 1.0000000 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 Tegmen

Tegmen has a spectral type of G0V. This means the star is a white to yellow main sequence dwarf star. The star is 7420.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24201.3201248000000000s. The star has a B-V Colour Index of 0.53 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,162 Kelvin.

Tegmen Radius has been calculated as being 2.44 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,697,925.47.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.40. 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 0.12 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 2.20 and 2.40 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

The star has companion stars which are in orbit close by, it has at least the following companions in close orbit, .

Tegmen Apparent and Absolute Magnitudes

Tegmen has an apparent magnitude of 4.67 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 2.63 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.67. 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 Tegmen

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 39.11 which gave the calculated distance to Tegmen as 83.40 light years away from Earth or 25.57 parsecs. It would take a spaceship travelling at the speed of light, 83.40 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 39.87 which put Tegmen at a distance of 81.81 light years or 25.08 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.

The star's Galacto-Centric Distance is 7,420.00 Parsecs or 24,201.32 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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.

Tegmen Facts

Alternative Names

Traditional/Proper NameTegmen
Short Name16 Cnc
Bayer DesignationZeta Cancri
Alternative Name(s)Tegmine,16 Cancri
Hipparcos Library I.D.40167
Yale Bright Star Catalogue (HR) Id3208
Bonner DurchmusterungBDD+18 1867
Henry Draper Designation68255

Visual Facts

Star Typemain sequence dwarf star
Age2.30 Billion Years Old
Age Range2.20 - 2.40 Billion Years Old
Absolute Magnitude2.63 / 2.67
Visual / Apparent Magnitude4.67
Naked Eye VisibleYes - Ref: Wiki
Right Ascension (R.A.)08h 12m 12.71
Declination (Dec.)+17d38`53.3
Galactic Latitude25.53 degrees
Galactic Longitude205.30 degrees
1997 Distance from Earth39.11 Parallax (milliarcseconds)
 83.40 Light Years
 25.57 Parsecs
2007 Revised Distance from Earth39.87 Parallax (milliarcseconds)
 81.81 Light Years
 25.08 Parsecs
Galacto-Centric Distance24,201.32 Light Years / 7,420.00 Parsecs
Proper Motion Dec.-151.73 ± 0.82 milliarcseconds/year
Proper Motion RA.27.61 ± 0.82 milliarcseconds/year
B-V Index0.53
Radial Velocity-7.93 ± 0.08 km/s
Iron Abundance0.12 ± 0.08 Fe/H
Spectral TypeG0V
Colour(G) White to Yellow
Stars in Solar System4

Estimated Facts

Luminosity (x the Sun)1.0000000
Calculated Effective Temperature6,162 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
68257+18 1867.0A5.6000042.00000-139.00000F7Yellow/White
68256B6.000001826
68255C6.3000099.00000-113.00000G2Yellow1960

Location of Tegmen in Cancer


Tegmen (Zeta Cancri) Location in Cancer

The map was generated using Night Vision, an awesome free application by Brian Simpson.


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