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GU Canis Majoris, , HD52721, HIP33868

GU Canis Majoris is a blue eclipsing binary system main sequence dwarf star that can be located in the constellation of CanisMajor. The star can not be seen by the naked eye, you need a telescope to see it.

HIP33868 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD52721.

GU Canis Majoris has alternative name(s), GU CMa.

Location of GU Canis Majoris

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 GU Canis Majoris, the location is 07h 01m 49.51 and -11d18`03.4 .

Proper Motion of GU Canis Majoris

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 4.59 ± 1.54 miliarcseconds/year towards the north and -5.08 ± 2.04 miliarcseconds/year east if we saw them in the horizon.

GU Canis Majoris 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 3190.0000000 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 GU Canis Majoris

GU Canis Majoris has a spectral type of B2Vne. This means the star is a blue main sequence dwarf star. The star has a B-V Colour Index of 0.01 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,392 Kelvin.

GU Canis Majoris Radius has been calculated as being 15.76 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 10,962,347.62.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 7.72. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

GU Canis Majoris Apparent and Absolute Magnitudes

GU Canis Majoris has an apparent magnitude of 6.54 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 -3.25 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.70. 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 GU Canis Majoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.10 which gave the calculated distance to GU Canis Majoris as 2965.12 light years away from Earth or 909.09 parsecs. It would take a spaceship travelling at the speed of light, 2965.12 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 2.25 which put GU Canis Majoris at a distance of 1449.61 light years or 444.44 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 GU Canis Majoris

The star is a eclipsing binary system Beta Lyrae (Sheliak) 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. GU Canis Majoris brightness ranges from a magnitude of 6.751 to a magnitude of 6.521 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 1.6 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.

GU Canis Majoris Facts

Alternative Names

Traditional/Proper NameGU Canis Majoris
Short NameGU CMa
Hipparcos Library I.D.33868
Bonner DurchmusterungBD-11 1747
Henry Draper Designation52721

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude-3.25 / -1.70
Visual / Apparent Magnitude6.54
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)07h 01m 49.51
Declination (Dec.)-11d18`03.4
Galactic Latitude-2.86 degrees
Galactic Longitude224.17 degrees
1997 Distance from Earth1.10 Parallax (milliarcseconds)
 2965.12 Light Years
 909.09 Parsecs
2007 Revised Distance from Earth2.25 Parallax (milliarcseconds)
 1449.61 Light Years
 444.44 Parsecs
Proper Motion Dec.4.59 ± 1.54 milliarcseconds/year
Proper Motion RA.-5.08 ± 2.04 milliarcseconds/year
B-V Index0.01
Radial Velocity23.00 ± 1.50 km/s
Spectral TypeB2Vne
Colour(B) blue

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeBeta Lyrae (Sheliak)
Mean Variability Period in Days1.610
Variable Magnitude Range (Brighter - Dimmer)6.521 - 6.751

Estimated Facts

Luminosity (x the Sun)3,190.0000000
Calculated Effective Temperature9,392 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.


Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
52721-11 1747.0A7.10000-25.0000011.00000B3Blue/White
B7.800001900

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