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Omega Orionis, 47 Orionis, HD37490, HIP26594, HR1934

Omega Orionis is a blue eruptive giant star that can be located in the constellation of Orion. Omega Orionis is the brightest star in Orion 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.

Omega Orionis is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR1934. HIP26594 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD37490.

Omega Orionis has alternative name(s), ome Ori.

Location of Omega Orionis

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 Orionis, the location is 05h 39m 11.15 and +04d 07` 17.3 .

Proper Motion of Omega Orionis

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 0.00 ± 0.15 miliarcseconds/year towards the north and 0.84 ± 0.29 miliarcseconds/year east if we saw them in the horizon.

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

Omega Orionis has a spectral type of B3IIIe. This means the star is a blue giant star. The star is 7744.00000000 Parsecs from the Galactic Centre or terms of Light Years is 25258.0893593600000000s. The star has a B-V Colour Index of -0.09 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 11,375 Kelvin.

Omega Orionis Radius has been calculated as being 15.03 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 10,459,817.17.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 12.85. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Omega Orionis Apparent and Absolute Magnitudes

Omega Orionis has an apparent magnitude of 4.50 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 -3.98 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.64. 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 Orionis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.01 which gave the calculated distance to Omega Orionis as 1622.70 light years away from Earth or 497.51 parsecs. It would take a spaceship travelling at the speed of light, 1622.70 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 2.36 which put Omega Orionis at a distance of 1382.05 light years or 423.73 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 7,744.00 Parsecs or 25,258.09 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of Omega Orionis

The star is a eruptive Gamma Cassiopeiae variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. Omega Orionis brightness ranges from a magnitude of 4.531 to a magnitude of 4.444 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 days (variability).

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.

Omega Orionis Facts

Alternative Names

Flamsteed Name47 Orionis
Flamsteed Short Name47 Ori
Short Nameome Ori
Bayer DesignationOmega Orionis
Hipparcos Library I.D.26594
Yale Bright Star Catalogue (HR) Id1934
Bonner DurchmusterungBD+04 1002
Henry Draper Designation37490

Visual Facts

Star Typegiant star
Absolute Magnitude-3.98 / -3.64
Visual / Apparent Magnitude4.50
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)05h 39m 11.15
Declination (Dec.)+04d 07` 17.3
Galactic Latitude-14.03 degrees
Galactic Longitude200.73 degrees
1997 Distance from Earth2.01 Parallax (milliarcseconds)
 1622.70 Light Years
 497.51 Parsecs
2007 Revised Distance from Earth2.36 Parallax (milliarcseconds)
 1382.05 Light Years
 423.73 Parsecs
Galacto-Centric Distance25,258.09 Light Years / 7,744.00 Parsecs
Proper Motion Dec.0.00 ± 0.15 milliarcseconds/year
Proper Motion RA.0.84 ± 0.29 milliarcseconds/year
B-V Index-0.09
Radial Velocity20.50 ± 0.90 km/s
Spectral TypeB3IIIe
Colour(B) blue

Variable Star Details

Variable Star ClassEruptive
Variable Star TypeGamma Cassiopeiae
Mean Variability Period in Days0.059
Variable Magnitude Range (Brighter - Dimmer)4.444 - 4.531

Estimated Facts

Calculated Effective Temperature11,375 Kelvin

Sources and Links

SIMBAD SourceLink

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