Universe Guide


Tien Kwan (Zeta Tauri) - HD37202 - HIP26451

Tien Kwan (Zeta Tauri) is a blue eclipsing binary system giant star that can be located in the constellation of Taurus. Zeta Tauri is the Bayer Classification for the star. HIP26451 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD37202. Tien Kwan has alternative name(s), Zeta Tau,123 Tauri , zet_Tau, 123 Tau.

Location of Tien Kwan

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 Tien Kwan, the location is 05h 37m 38.68 and +21d08`33.3 .

Proper Motion of Tien Kwan

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 -020.07 ± 000.50 towards the north and 001.78 ± 000.82 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Tien Kwan

Tien Kwan has a spectral type of B4IIIp. This means the star is a blue giant star. The star has a B-V Colour Index of -0.14 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 13,196 Kelvin.

Tien Kwan has been calculated as 5.81 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 4,041,367.54.km.

Tien Kwan Apparent and Absolute Magnitudes

Tien Kwan has an apparent magnitude of 2.97 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 -2.56 If you used the 2007 Parallax value, you would get an absolute magnitude of -2.70. 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 Tien Kwan

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 7.82 which gave the calculated distance to Tien Kwan as 417.09 light years away from Earth or 127.88 parsecs. It would take a spaceship travelling at the speed of light, 417.09 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 7.33 which put Tien Kwan at a distance of 444.97 light years or 136.43 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.

Variable Type of Tien Kwan

The star is a eclipsing binary system Eclipsing variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. This is a some uncertainty as to the type but the type mentioned is the current variable star classification for this star. Tien Kwan brightness ranges from a magnitude of 3.000 to a magnitude of 3.000 over its variable period. The smaller the magnitude, the brighter the star.

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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Tien Kwan Facts

Alternative Names

Traditional NameTien Kwan
Short Namezet Tau, 123 Tau
Bayer DesignationZeta Tauri
Alternative Name(s)Zeta Tau,123 Tauri
Hipparcos Library I.D.26451
Bonner DurchmusterungBD+21 908
Henry Draper Designation37202

Visual Facts

Star Typegiant star
Absolute Magnitude-2.56 / -2.70
Apparent Magnitude2.97
Right Ascension (R.A.)05h 37m 38.68
Declination (Dec.)+21d08`33.3
1997 Distance from Earth7.82 Parallax (milliarcseconds)
 417.09 Light Years
 127.88 Parsecs
2007 Revised Distance from Earth7.33 Parallax (milliarcseconds)
 444.97 Light Years
 136.43 Parsecs
Proper Motion Dec.-20.07 ± 0.50 milliarcseconds/year
Proper Motion RA.1.78 ± 0.82 milliarcseconds/year
B-V Index-0.14
Spectral TypeB4IIIp
Colour(B) blue

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeEclipsing probably

Estimated Facts

Radius (x the Sun)5.81
Calculated Effective Temperature13,196 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Add a Comment

Email: (Optional)