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KW Sagittarii, HD316496, HIP87433

KW Sagittarii is a red pulsating very luminous supergiant star that can be located in the constellation of Sagittarius. The star can not be seen by the naked eye, you need a telescope to see it.

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

Location of KW Sagittarii

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 -28d 01` 20.5 .

KW Sagittarii Luminosity

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.

Physical Properties (Colour, Temperature, Radius) of KW Sagittarii

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. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

KW Sagittarii Apparent and Absolute Magnitudes

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.

Distance to KW Sagittarii

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.

Variable Type of KW Sagittarii

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).

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.

KW Sagittarii Facts

Alternative Names

Traditional/Proper NameKW Sagittarii
Short NameKW Sgr
Hipparcos Library I.D.87433
Henry Draper Designation316496

Visual Facts

Star Typesupergiant star
Visual / Apparent Magnitude8.58
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)17h 52m 00.73
Declination (Dec.)-28d 01` 20.5
Galactic Latitude-0.73 degrees
Galactic Longitude1.51 degrees
Distance from Earth-2.40 Parallax (milliarcseconds)
 -1359.01 Light Years
 -416.67 Parsecs
B-V Index3.31
Radial Velocity-7.40 ± 999.00 km/s
Spectral TypeM0I-M4Ia
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemiregular late- (M, C, S or Me, Ce, Se) supergiants (Mu Cep)
Mean Variability Period in Days0.260
Variable Magnitude Range (Brighter - Dimmer)8.413 - 8.692

Estimated Facts

Luminosity (x the Sun)50,600.0000000

Sources and Links

SIMBAD SourceLink

Related Stars

Location of KW Sagittarii in Sagittarius

KW Sagittarii Location in Sagittarius

The map was generated using Night Vision, an awesome free application by Brian Simpson.

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