Universe Guide


Omega Eridani - HD31109 - HIP22701

Omega Eridani is a blue subgiant star that can be located in the constellation of Eridanus. Omega Eridani is the Bayer Classification for the star. HIP22701 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD31109. The Id of the star in the Gould Star Catalogue is 276. 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. Omega Eridani has alternative name(s), 61 Eridani , 61 Eri.

Location of Omega Eridani

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 Omega Eridani, the location is 04h 52m 53.68 and -05d27`09.9 .

Proper Motion of Omega Eridani

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 025.57 ± 000.14 towards the north and -017.86 ± 000.24 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Omega Eridani

Omega Eridani has a spectral type of A9IV. This means the star is a blue subgiant star. The star has a B-V Colour Index of 0.25 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,483 Kelvin.

Omega Eridani has been calculated as 5.19 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,607,736.97.km.

Omega Eridani Apparent and Absolute Magnitudes

Omega Eridani has an apparent magnitude of 4.36 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 0.15 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.07. 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 Omega Eridani

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 14.39 which gave the calculated distance to Omega Eridani as 226.66 light years away from Earth or 69.49 parsecs. It would take a spaceship travelling at the speed of light, 226.66 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 13.88 which put Omega Eridani at a distance of 234.99 light years or 72.05 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.

Omega Eridani Facts

Alternative Names

Short Name61 Eri
Bayer DesignationOmega Eridani
Alternative Name(s)61 Eridani
Hipparcos Library I.D.22701
Bonner DurchmusterungBD-05 1068
Gould I.D.276
Henry Draper Designation31109

Visual Facts

Star Typesubgiant star
Absolute Magnitude0.15 / 0.07
Apparent Magnitude4.36
Right Ascension (R.A.)04h 52m 53.68
Declination (Dec.)-05d27`09.9
1997 Distance from Earth14.39 Parallax (milliarcseconds)
 226.66 Light Years
 69.49 Parsecs
2007 Revised Distance from Earth13.88 Parallax (milliarcseconds)
 234.99 Light Years
 72.05 Parsecs
Proper Motion Dec.25.57 ± 0.14 milliarcseconds/year
Proper Motion RA.-17.86 ± 0.24 milliarcseconds/year
B-V Index0.25
Spectral TypeA9IV
Colour(A) blue

Estimated Facts

Radius (x the Sun)5.19
Calculated Effective Temperature7,483 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Add a Comment

Email: (Optional)