KW Sagittarii is a red pulsating supergiant star that can be located in the constellation of Sagittarius. The description is based on the spectral class. The star can not be seen by the naked eye, you need a telescope to see it.
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
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.
More details on star alternative names can be found at Star Names .
The location of the star in the night sky 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 -28° 01` 20.5 .
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. Using the supplied 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 8.692 to a magnitude of 8.413 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.3 days (variability).
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.
|Primary / Proper / Traditional Name||KW Sagittarii|
|Alternative Names||HD 316496, HIP 87433, KW Sgr|
|Multiple Star System||No / Unknown|
|Star Type||very luminous Supergiant Star|
|Visual / Apparent Magnitude||8.58|
|Naked Eye Visible||Requires a 7x50 Binoculars - Magnitudes|
|Right Ascension (R.A.)||17h 52m 00.73|
|Declination (Dec.)||-28° 01` 20.5|
|Galactic Latitude||-0.73 degrees|
|Galactic Longitude||1.51 degrees|
|Distance from Earth||-2.40 Parallax (milliarcseconds)|
|-1359.01 Light Years|
|Radial Velocity||-7.40 ± 999.00 km/s|
|Variable Star Class||Pulsating|
|Variable Star Type||Semiregular late- (M, C, S or Me, Ce, Se) supergiants (Mu Cep)|
|Mean Variability Period in Days||0.260|
|Variable Magnitude Range (Brighter - Dimmer)||8.413 - 8.692|