Universe Guide

122 G. Eri - HD23281 - HIP17395

122 G. Eri is a blue less luminous star that can be located in the constellation of Eridanus. HIP17395 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD23281. The Id of the star in the Gould Star Catalogue is 122. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major.

Location of 122 G. Eri

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 from celestial equator. The Declination is how up or down compared to the celestial equator and is expressed in degrees. For 122 G. Eri, the location is 03h 43m 33.84 and -10 d 29`08.2 .

Proper Motion of 122 G. Eri

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 -018.00 ± 000.00 towards the north and -008.00 ± 000.00 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 122 G. Eri

122 G. Eri has a spectral type of A5m. This means the star is a blue coloured less luminous star. The star has a B-V Colour Index of 0.21 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,325 Kelvin.

122 G. Eri has been calculated as 1.92 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,335,823.29.km.

122 G. Eri Apparent and Absolute Magnitudes

122 G. Eri has an apparent magnitude of 5.59 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 2.40 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.49. 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 122 G. Eri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 23.00 which gave the calculated distance to 122 G. Eri as 141.81 light years away from us or 43.48 parsecs. In 2007, Hipparcos data was revised with a new parallax of 24.00 which put 122 G. Eri at a distance of 135.90 light years or 41.67 parsecs.

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.

122 G. Eri Facts

Traditional Name122 G. Eri
Hipparcos Library I.D.17395
Gould I.D.122
Henry Draper Designation23281
Celestial TypeStar
Absolute Magnitude2.40 / 2.49
Apparent Magnitude5.59
Right Ascension (R.A.)03h 43m 33.84
Declination (Dec.)-10 d 29`08.2
1997 Distance23.00 Parallax (milliarcseconds)
 141.81 Light Years
 43.48 Parsecs
2007 Distance24.00 Parallax (milliarcseconds)
 135.90 Light Years
 41.67 Parsecs
Proper Motion Dec.-18.00 ± 0.00 milliarcseconds/year
Proper Motion RA.-8.00 ± 0.00 milliarcseconds/year
B-V Index0.21
Spectral TypeA5m
Colour(A) blue
Star Typeless luminous star
Radius (x the Sun)1.92
Calculated Effective Temperature7,325 Kelvin

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