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Kapteyn's Star, HD33793, HIP24186

Kapteyn's Star is a red main sequence dwarf star that can be located in the constellation of Pictor. Kapteyn's Star is the brightest star in Pictor based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.

HIP24186 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD33793. The Gliese ID of the star is Gliese GL191. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Ref : Star Names.

Kapteyn's Star has alternative name(s), VZ Pic. Kapteyn's Star has at least 2 Extrasolar Planets believed to be in orbit around the star.

Location of Kapteyn's Star

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 Kapteyn's Star, the location is 05h 11m 35.21 and -45d 00` 16.2 .

Proper Motion of Kapteyn's Star

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 -5,730.84 ± 0.81 miliarcseconds/year towards the north and 6,505.08 ± 0.91 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Kapteyn's Star

Kapteyn's Star has a spectral type of M0V. This means the star is a red main sequence dwarf star. The star is 7401.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24139.3490894400000000s. The star has a B-V Colour Index of 1.54 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,913 Kelvin.

Kapteyn's Star Radius has been calculated as being 0.13 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 93,812.61.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 0.13. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.91 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Kapteyn's Star Apparent and Absolute Magnitudes

Kapteyn's Star has an apparent magnitude of 8.86 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 10.89 If you used the 2007 Parallax value, you would get an absolute magnitude of 10.90. 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 Kapteyn's Star

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 255.26 which gave the calculated distance to Kapteyn's Star as 12.78 light years away from Earth or 3.92 parsecs. It would take a spaceship travelling at the speed of light, 12.78 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 255.66 which put Kapteyn's Star at a distance of 12.76 light years or 3.91 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.

The star's Galacto-Centric Distance is 7,401.00 Parsecs or 24,139.35 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*. Kapteyn's Star brightness ranges from a magnitude of 9.221 to a magnitude of 8.904 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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.

Kapteyn's Star Facts

Alternative Names

Traditional/Proper NameKapteyn's Star
Short NameVZ Pic
Hipparcos Library I.D.24186
Gliese ID191
Henry Draper Designation33793

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude10.89 / 10.90
Visual / Apparent Magnitude8.86
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)05h 11m 35.21
Declination (Dec.)-45d 00` 16.2
Galactic Latitude-36.02 degrees
Galactic Longitude250.51 degrees
1997 Distance from Earth255.26 Parallax (milliarcseconds)
 12.78 Light Years
 3.92 Parsecs
2007 Revised Distance from Earth255.66 Parallax (milliarcseconds)
 12.76 Light Years
 3.91 Parsecs
Galacto-Centric Distance24,139.35 Light Years / 7,401.00 Parsecs
Proper Motion Dec.-5730.84 ± 0.81 milliarcseconds/year
Proper Motion RA.6505.08 ± 0.91 milliarcseconds/year
B-V Index1.54
Radial Velocity245.19 ± 0.10 km/s
Iron Abundance-0.91 ± 9.99 Fe/H
Spectral TypeM0V
Colour(M) Red

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count2

Variable Star Details

Mean Variability Period in Days0.224
Variable Magnitude Range (Brighter - Dimmer)8.904 - 9.221

Estimated Facts

Calculated Effective Temperature3,913 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Kapteyn's Star in Pictor

Kapteyn's Star Location in Pictor

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

List of Extrasolar Planets orbiting Kapteyn's Star

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastronInclination
Kapteyn's bConfirmed0.00314648.6160.2120140.16880.4002014.000
Kapteyn's cConfirmed0.003776121.5400.2320140.3112014.000

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