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HomeFactsConstellationsCanis Major

Mirzam, Beta Canis Majoris, 2 Canis Majoris, HD44743, HIP30324, HR2294

Mirzam (Beta Canis Majoris) is a blue pulsating giant star that can be located in the constellation of CanisMajor. Mirzam is the 47th brightest star in the night sky and the 4th brightest star in Canis Major based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Beta Canis Majoris is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR2294. HIP30324 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD44743.

Mirzam has alternative name(s), bet CMa.

Location of Mirzam

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 Mirzam, the location is 06h 22m 41.99 and -17d 57` 21.3 .

Proper Motion of Mirzam

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 -0.78 ± 0.15 miliarcseconds/year towards the north and -3.23 ± 0.22 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Mirzam

Mirzam has a spectral type of B1II/III. This means the star is a blue giant star. The star is 7502.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24468.7740668800000000s. The star has a B-V Colour Index of -0.24 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 21,255 Kelvin.

Mirzam Radius has been calculated as being 4.25 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,954,638.76.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 4.19. 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 -0.41 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Mirzam Apparent and Absolute Magnitudes

Mirzam has an apparent magnitude of 1.98 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 -3.95 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.92. 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 Mirzam

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 6.53 which gave the calculated distance to Mirzam as 499.48 light years away from Earth or 153.14 parsecs. It would take a spaceship travelling at the speed of light, 499.48 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 6.62 which put Mirzam at a distance of 492.69 light years or 151.06 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 7,502.00 Parsecs or 24,468.77 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of Mirzam

The star is a pulsating Beta Cephei 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. Mirzam brightness ranges from a magnitude of 1.902 to a magnitude of 1.880 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.

Mirzam Facts

Alternative Names

Traditional/Proper NameMirzam
Flamsteed Name2 Canis Majoris
Flamsteed Short Name2 CMa
Short Namebet CMa
Bayer DesignationBeta Canis Majoris
Hipparcos Library I.D.30324
Yale Bright Star Catalogue (HR) Id2294
Bonner DurchmusterungBD-17 1467
Henry Draper Designation44743

Visual Facts

Star Typegiant star
ConstellationCanis Major
Absolute Magnitude-3.95 / -3.92
Visual / Apparent Magnitude1.98
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)06h 22m 41.99
Declination (Dec.)-17d 57` 21.3
Galactic Latitude-14.27 degrees
Galactic Longitude226.06 degrees
1997 Distance from Earth6.53 Parallax (milliarcseconds)
 499.48 Light Years
 153.14 Parsecs
2007 Revised Distance from Earth6.62 Parallax (milliarcseconds)
 492.69 Light Years
 151.06 Parsecs
Galacto-Centric Distance24,468.77 Light Years / 7,502.00 Parsecs
Proper Motion Dec.-0.78 ± 0.15 milliarcseconds/year
Proper Motion RA.-3.23 ± 0.22 milliarcseconds/year
B-V Index-0.24
Radial Velocity33.70 ± 0.50 km/s
Iron Abundance-0.41 ± 9.99 Fe/H
Spectral TypeB1II/III
Brightest in Night Sky47th
Colour(B) blue

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeBeta Cephei
Mean Variability Period in Days0.251
Variable Magnitude Range (Brighter - Dimmer)1.880 - 1.902

Estimated Facts

Calculated Effective Temperature21,255 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
44743-17 1467.0A2.00000-13.00000-4.00000B1Blue/White
-17 1466.0B9.800001908

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asdf asdfTuesday, 26th April 2016 7:42:29 PM
When will it burn out and what will it become?