Universe Guide


66 Orionis, HD41380, HIP28814

66 Orionis is a white to yellow giant star that can be located in the constellation of Orion. 66 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.

HIP28814 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD41380.

Location of 66 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 66 Orionis, the location is 06h 04m 58.36 and +04d09`31.2 .

Proper Motion of 66 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 -3.05 ± 0.51 miliarcseconds/year towards the north and -0.99 ± 0.79 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 66 Orionis

66 Orionis has a spectral type of G4III. This means the star is a white to yellow giant star. The star has a B-V Colour Index of 1.04 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,773 Kelvin.

66 Orionis Radius has been calculated as being 77.87 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 54,180,383.13.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 148.38. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.22 with an error value of 0.06 Fe/H with the Sun has a value of 1 to put it into context.

66 Orionis Apparent and Absolute Magnitudes

66 Orionis has an apparent magnitude of 5.63 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 -3.78 If you used the 2007 Parallax value, you would get an absolute magnitude of -5.18. 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 66 Orionis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.31 which gave the calculated distance to 66 Orionis as 2489.80 light years away from Earth or 763.36 parsecs. It would take a spaceship travelling at the speed of light, 2489.80 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 0.69 which put 66 Orionis at a distance of 4727.00 light years or 1449.28 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 Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

66 Orionis Facts

Alternative Names

Traditional/Proper Name66 Orionis
Flamsteed Name66 Orionis
Flamsteed Short Name66 Ori
Hipparcos Library I.D.28814
Bonner DurchmusterungBD+04 1116
Henry Draper Designation41380

Visual Facts

Star Typegiant star
Absolute Magnitude-3.78 / -5.18
Visual / Apparent Magnitude5.63
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)06h 04m 58.36
Declination (Dec.)+04d09`31.2
Galactic Latitude-8.38 degrees
Galactic Longitude203.85 degrees
1997 Distance from Earth1.31 Parallax (milliarcseconds)
 2489.80 Light Years
 763.36 Parsecs
2007 Revised Distance from Earth0.69 Parallax (milliarcseconds)
 4727.00 Light Years
 1449.28 Parsecs
Proper Motion Dec.-3.05 ± 0.51 milliarcseconds/year
Proper Motion RA.-0.99 ± 0.79 milliarcseconds/year
B-V Index1.04
Radial Velocity25.02 ± 0.05 km/s
Iron Abundance-0.22 ± 0.06 Fe/H
Spectral TypeG4III
Colour(G) White to Yellow

Estimated Facts

Calculated Effective Temperature4,773 Kelvin

Sources and Links

SIMBAD SourceLink

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