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Gamma3 Octantis, HD636, HIP814

Gamma3 Octantis is a orange to red giant star that can be located in the constellation of Octans. Gamma3 Octantis is the brightest star in Octans based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Gamma3 Octantis is the Bayer Classification for the star. HIP814 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD636.

Location of Gamma3 Octantis

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 Gamma3 Octantis, the location is 00h 10m 02.27 and -82d13`26.4 .

Proper Motion of Gamma3 Octantis

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 -20.34 ± 0.15 miliarcseconds/year towards the north and -21.65 ± 0.19 miliarcseconds/year east if we saw them in the horizon.

Gamma3 Octantis 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 82.0000000 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, Radius) of Gamma3 Octantis

Gamma3 Octantis has a spectral type of K1/K2III. This means the star is a orange to red giant star. The star is 7364.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24018.6686521600000000s. The star has a B-V Colour Index of 1 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,849 Kelvin.

Gamma3 Octantis Radius has been calculated as being 8.62 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 5,998,937.42.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 9.03. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Gamma3 Octantis Apparent and Absolute Magnitudes

Gamma3 Octantis has an apparent magnitude of 5.29 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 0.93 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.83. 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 Gamma3 Octantis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 13.45 which gave the calculated distance to Gamma3 Octantis as 242.50 light years away from Earth or 74.35 parsecs. It would take a spaceship travelling at the speed of light, 242.50 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 12.81 which put Gamma3 Octantis at a distance of 254.62 light years or 78.06 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.

The star's Galacto-Centric Distance is 7,364.00 Parsecs or 24,018.67 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.

Gamma3 Octantis Facts

Alternative Names

Bayer DesignationGamma3 Octantis
Hipparcos Library I.D.814
Henry Draper Designation636

Visual Facts

Star Typegiant star
Absolute Magnitude0.93 / 0.83
Visual / Apparent Magnitude5.29
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)00h 10m 02.27
Declination (Dec.)-82d13`26.4
Galactic Latitude-34.77 degrees
Galactic Longitude304.63 degrees
1997 Distance from Earth13.45 Parallax (milliarcseconds)
 242.50 Light Years
 74.35 Parsecs
2007 Revised Distance from Earth12.81 Parallax (milliarcseconds)
 254.62 Light Years
 78.06 Parsecs
Galacto-Centric Distance24,018.67 Light Years / 7,364.00 Parsecs
Proper Motion Dec.-20.34 ± 0.15 milliarcseconds/year
Proper Motion RA.-21.65 ± 0.19 milliarcseconds/year
B-V Index1.00
Radial Velocity15.00 ± 2.80 km/s
Spectral TypeK1/K2III
Colour(K) Orange to Red

Estimated Facts

Luminosity (x the Sun)82.0000000
Calculated Effective Temperature4,849 Kelvin

Sources and Links

SIMBAD SourceLink

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