Upsilon2 Centauri is a blue to white luminous giant star that can be located in the constellation of Centaurus. Upsilon2 Centauri is the brightest star in Centaurus 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.
Upsilon2 Centauri is the Bayer Classification for the star. HIP68523 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD122223. The Id of the star in the Gould Star Catalogue is 303. 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.
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 Upsilon2 Centauri, the location is 14h 01m 43.49 and -45d36`12.1 .
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 -16.25 ± 0.69 miliarcseconds/year towards the north and 8.64 ± 1.05 miliarcseconds/year east if we saw them in the horizon.
Upsilon2 Centauri has a spectral type of F6II. This means the star is a blue to white luminous giant star. The star has a B-V Colour Index of 0.59 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,898 Kelvin.
Upsilon2 Centauri Radius has been calculated as being 16.65 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 11,587,548.03.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 47.16. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.
Upsilon2 Centauri has an apparent magnitude of 4.34 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 -1.35 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.61. 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.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 7.28 which gave the calculated distance to Upsilon2 Centauri as 448.03 light years away from Earth or 137.36 parsecs. It would take a spaceship travelling at the speed of light, 448.03 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 2.57 which put Upsilon2 Centauri at a distance of 1269.12 light years or 389.11 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.
|Bayer Designation||Upsilon2 Centauri|
|Hipparcos Library I.D.||68523|
|Henry Draper Designation||122223|
|Star Type||luminous giant star|
|Absolute Magnitude||-1.35 / -3.61|
|Visual / Apparent Magnitude||4.34|
|Naked Eye Visible||Yes - Magnitudes|
|Right Ascension (R.A.)||14h 01m 43.49|
|Galactic Latitude||15.53 degrees|
|Galactic Longitude||315.60 degrees|
|1997 Distance from Earth||7.28 Parallax (milliarcseconds)|
|448.03 Light Years|
|2007 Revised Distance from Earth||2.57 Parallax (milliarcseconds)|
|1269.12 Light Years|
|Proper Motion Dec.||-16.25 ± 0.69 milliarcseconds/year|
|Proper Motion RA.||8.64 ± 1.05 milliarcseconds/year|
|Radial Velocity||-7.80 ± 7.40 km/s|
|Colour||(F) blue to white|
|Calculated Effective Temperature||5,898 Kelvin|