WR 18 is a Wolf-Rayet star that can be located in the constellation of Carina. HIP50368 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD89358. WR 18 has alternative name(s), V500_Car.
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 WR 18, the location is 10h 17m 02.28 and -57d54`46.9 .
The star is a Wolf-Rayet, a rare type of star of which not many are known. These stars are extremely luminous and large compared to our Sun. They live fast and die hard in a matter of millions not billions of years like our Sun. They exhaust their hydrogen supplies, turning to other gasses and expand outwards with massive solar winds, moving a step closer in the stellar evolution towards their death in a super or hypernova explosion.
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 005.18 ± 001.30 towards the north and -005.41 ± 001.61 east if we saw them in the horizon.
WR 18 has a spectral type of WN5. This means the star is a Wolf-Rayet star. The star has a B-V Colour Index of 0.49 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,140 Kelvin.
WR 18 has been calculated as 6.62 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 4,603,057.24.km.
WR 18 has an apparent magnitude of 10.64 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 0.48 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.78. 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 0.93 which gave the calculated distance to WR 18 as 3507.13 light years away from Earth or 1075.27 parsecs. It would take a spaceship travelling at the speed of light, 3507.13 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 0.52 which put WR 18 at a distance of 6272.37 light years or 1923.08 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. WR 18 brightness ranges from a magnitude of 11.000 to a magnitude of 11.000 over its variable period. The smaller the magnitude, the brighter the star.
|Traditional Name||WR 18|
|Short Name||V500 Car|
|Hipparcos Library I.D.||50368|
|Henry Draper Designation||89358|
|Star Type||Wolf-Rayet star|
|Absolute Magnitude||0.48 / -0.78|
|Right Ascension (R.A.)||10h 17m 02.28|
|1997 Distance from Earth||0.93 Parallax (milliarcseconds)|
|3507.13 Light Years|
|2007 Revised Distance from Earth||0.52 Parallax (milliarcseconds)|
|6272.37 Light Years|
|Proper Motion Dec.||5.18 ± 1.30 milliarcseconds/year|
|Proper Motion RA.||-5.41 ± 1.61 milliarcseconds/year|
|Radius (x the Sun)||6.62|
|Calculated Effective Temperature||6,140 Kelvin|