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Gamma Tucanae

Gamma Tucanae Facts

Gamma Tucanae's Alternative Names

Gamma Tucanae (Gam Tuc) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in the early nineteenth century. The brightest star in the constellation is normally given the Alpha designation although there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR8848. HIP114996 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD219571.

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

Location of Gamma Tucanae

The location of the giant 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 Gamma Tucanae, the location is 23h 17m 25.81 and -58° 14` 09.3 .

Radial Velocity and Proper Motion of Gamma Tucanae

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 81.16 ± 0.39 miliarcseconds/year towards the north and -35.83 ± 0.63 miliarcseconds/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 18.40 km/s with an error of about 0.70 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.

Gamma Tucanae 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 11.33 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature, Age) of Gamma Tucanae

Gamma Tucanae Colour and Temperature

Gamma Tucanae has a spectral type of F1III. This means the star is a blue to white giant star. The star has a B-V Colour Index of 0.41 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,681 Kelvin.

Gamma Tucanae Radius

Radius has been calculated as being 2.45 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,704,835.97.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 2.55. 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 -0.22 with an error value of 0.03 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 1.70 Billion years old but could be between 1.60 and 1.80 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

Gamma Tucanae Apparent and Absolute Magnitudes

Gamma Tucanae has an apparent magnitude of 3.99 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 2.27 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.18. 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 Gamma Tucanae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 45.40 which gave the calculated distance to Gamma Tucanae as 71.84 light years away from Earth or 22.03 parsecs. It would take a spaceship travelling at the speed of light, 71.84 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 43.37 which put Gamma Tucanae at a distance of 75.20 light years or 23.06 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 4,756,433.29 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 7,389.00 Parsecs or 24,100.21 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.

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Additional Gamma Tucanae Facts and Figures

Visual Facts


Primary / Proper / Traditional NameGamma Tucanae
Alternative NamesGam Tuc, HD 219571, HIP 114996, HR 8848
Spectral TypeF1III
Constellation's Main StarYes
Multiple Star SystemNo / Unknown
Star TypeGiant Star
ColourYellow - White
GalaxyMilky Way
ConstellationTucana
Age1.70 Billion Years Old
Age Range1.60 - 1.80 Billion Years Old
Absolute Magnitude 2.27 / 2.18
Visual / Apparent Magnitude3.99
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)23h 17m 25.81
Declination (Dec.)-58° 14` 09.3
Galactic Latitude-54.82 degrees
Galactic Longitude324.30 degrees
1997 Distance from Earth45.40 Parallax (milliarcseconds)
 71.84 Light Years
 22.03 Parsecs
2007 Distance from Earth43.37 Parallax (milliarcseconds)
 75.20 Light Years
 23.06 Parsecs
 4,756,433.29 Astronomical Units
Galacto-Centric Distance24,100.21 Light Years / 7,389.00 Parsecs
Proper Motion Dec.81.16 ± 0.39 milliarcseconds/year
Proper Motion RA.-35.83 ± 0.63 milliarcseconds/year
B-V Index0.41
Radial Velocity18.40 ± 0.70 km/s
Iron Abundance-0.22 ± 0.03 Fe/H
Eccentricity0.21
Semi-Major Axis8826.00
Stellar Luminosity (Lsun)11.33

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Calculated Facts


Radius (x the Sun)2.55
Effective Temperature6,681 Kelvin

Sources and Links


SIMBAD SourceLink

Tucana Main Stars


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