KW Sagittarii is a red pulsating very luminous supergiant star that can be located in the constellation of Sagittarius. HIP87433 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD316496. KW Sagittarii has alternative name(s), KW_Sgr.
Along with its "neighbour" as in the same stretch of the sky, VX Sagittarii, it is one of the largest stars to have been so far discovered. If KW Sagittarii was at the centre of our Solar System, it would stretch out to past the orbit of Mars. The star that holds the largest star record is UY Scuti which stretches out past the orbit of Jupiter. The Earth would be inside its boundaries. It between 1,009 and 1,460 times the radius of the Sun. ref: Wiki
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 KW Sagittarii, the location is 17h 52m 00.73 and -28d01`20.5 .
Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 50600.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.
KW Sagittarii has a spectral type of M0I-M4Ia. This means the star is a red supergiant star. The star has a B-V Colour Index of 3.31 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 0 Kelvin.
KW Sagittarii has an apparent magnitude of 8.58 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 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 -2.40 which gave the calculated distance to KW Sagittarii as -1359.01 light years away from Earth or -416.67 parsecs. It would take a spaceship travelling at the speed of light, -1359.01 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
The star is a pulsating Semiregular late- (M, C, S or Me, Ce, Se) supergiants (Mu Cep) 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. KW Sagittarii brightness ranges from a magnitude of 9.000 to a magnitude of 8.000 over its variable period. The smaller the magnitude, the brighter the star.
|Traditional Name||KW Sagittarii|
|Short Name||KW Sgr|
|Hipparcos Library I.D.||87433|
|Henry Draper Designation||316496|
|Star Type||supergiant star|
|Right Ascension (R.A.)||17h 52m 00.73|
|1997 Distance from Earth||-2.40 Parallax (milliarcseconds)|
|-1359.01 Light Years|
|Variable Star Class||Pulsating|
|Variable Star Type||Semiregular late- (M, C, S or Me, Ce, Se) supergiants (Mu Cep)|
|Variable Magnitude Range (Brighter - Dimmer)||8.000 - 9.000|
|Luminosity (x the Sun)||50,600.0000000|