Universe Guide


SW Lacertae - HD216598 - HIP113052

SW Lacertae is a orange to red eclipsing main sequence dwarf star that can be located in the constellation of Lacerta. HIP113052 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD216598. SW Lacertae has alternative name(s), SW_Lac.

Location of SW Lacertae

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 SW Lacertae, the location is 22h 53m 41.59 and +37d56`18.5 .

Proper Motion of SW Lacertae

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 012.89 ± 000.94 towards the north and 087.93 ± 001.80 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of SW Lacertae

SW Lacertae has a spectral type of K0Vvar. This means the star is a orange to red main sequence dwarf star. The star has a B-V Colour Index of 0.75 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,418 Kelvin.

SW Lacertae has been calculated as 1.43 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 994,642.75.km.

SW Lacertae Apparent and Absolute Magnitudes

SW Lacertae has an apparent magnitude of 8.90 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 4.35 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.60. 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 SW Lacertae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 12.30 which gave the calculated distance to SW Lacertae as 265.17 light years away from Earth or 81.30 parsecs. It would take a spaceship travelling at the speed of light, 265.17 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 13.79 which put SW Lacertae at a distance of 236.52 light years or 72.52 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.

Variable Type of SW Lacertae

The star is a eclipsing W Ursae Majoris/Contact systems of the W UMa type, with ellipsoidal components of F0-K spectral type 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. SW Lacertae brightness ranges from a magnitude of 10.000 to a magnitude of 9.000 over its variable period. The smaller the magnitude, the brighter the star.

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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

SW Lacertae Facts

Alternative Names

Traditional NameSW Lacertae
Short NameSW Lac
Hipparcos Library I.D.113052
Bonner DurchmusterungBD+37 4717
Henry Draper Designation216598

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude4.35 / 4.60
Apparent Magnitude8.90
Right Ascension (R.A.)22h 53m 41.59
Declination (Dec.)+37d56`18.5
1997 Distance from Earth12.30 Parallax (milliarcseconds)
 265.17 Light Years
 81.30 Parsecs
2007 Revised Distance from Earth13.79 Parallax (milliarcseconds)
 236.52 Light Years
 72.52 Parsecs
Proper Motion Dec.12.89 ± 0.94 milliarcseconds/year
Proper Motion RA.87.93 ± 1.80 milliarcseconds/year
B-V Index0.75
Spectral TypeK0Vvar
Colour(K) Orange to Red

Variable Star Details

Variable Star ClassEclipsing
Variable Star TypeW Ursae Majoris/Contact systems of the W UMa type, with ellipsoidal components of F0-K spectral type
Variable Magnitude Range (Brighter - Dimmer)9.000 - 10.000

Estimated Facts

Radius (x the Sun)1.43
Calculated Effective Temperature5,418 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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