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Gamma Delphini (Gamma Delphini A) - HD197963 - HIP102531

Gamma Delphini (Gamma Delphini A) is a blue very luminous supergiant star that can be located in the constellation of Delphinus. Gamma Delphini A is the Bayer Classification for the star. HIP102531 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD197963. Gamma Delphini has alternative name(s), 12 Delphini , 12 Del. Gamma Delphini is a multiple star system with 2 stars orbiting in its solar system.

Location of Gamma Delphini

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 Gamma Delphini, the location is 20h 46m 38.87 and +16d07`28.6 .

Proper Motion of Gamma Delphini

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 -199.77 ± 000.57 towards the north and -025.47 ± 001.09 east if we saw them in the horizon.

Gamma Delphini 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 40000.0000000 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 Gamma Delphini

Gamma Delphini has a spectral type of A2Ia+.... This means the star is a blue supergiant star. The star has a B-V Colour Index of 0.49 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,140 Kelvin.

Gamma Delphini has been calculated as 2.44 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,694,435.62.km.

The star has a companion star which is in orbit close by, it has at least the following companions in close orbit, Gamma Delphini B.

Gamma Delphini Apparent and Absolute Magnitudes

Gamma Delphini has an apparent magnitude of 5.15 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 2.65 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.25. 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 Delphini

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 31.69 which gave the calculated distance to Gamma Delphini as 102.92 light years away from Earth or 31.56 parsecs. It would take a spaceship travelling at the speed of light, 102.92 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 26.35 which put Gamma Delphini at a distance of 123.78 light years or 37.95 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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Gamma Delphini Facts

Alternative Names

Traditional NameGamma Delphini
Short Name12 Del
Bayer DesignationGamma Delphini A
Alternative Name(s)12 Delphini
Hipparcos Library I.D.102531
Henry Draper Designation197963

Visual Facts

Star Typesupergiant star
Absolute Magnitude2.65 / 2.25
Apparent Magnitude5.15
Right Ascension (R.A.)20h 46m 38.87
Declination (Dec.)+16d07`28.6
1997 Distance from Earth31.69 Parallax (milliarcseconds)
 102.92 Light Years
 31.56 Parsecs
2007 Revised Distance from Earth26.35 Parallax (milliarcseconds)
 123.78 Light Years
 37.95 Parsecs
Proper Motion Dec.-199.77 ± 0.57 milliarcseconds/year
Proper Motion RA.-25.47 ± 1.09 milliarcseconds/year
B-V Index0.49
Spectral TypeA2Ia+...
Colour(A) blue

Companions (Multi-Star and Exoplanets) Facts

Stars in Solar System2
Companion StarsGamma Delphini B

Estimated Facts

Radius (x the Sun)2.44
Luminosity (x the Sun)40,000.0000000
Calculated Effective Temperature6,140 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars


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