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R Canis Majoris, HD57167, HIP35487

R Canis Majoris is a blue to white eclipsing subgiant star that can be located in the constellation of CanisMajor. R Canis Majoris is the 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. The star has an estimated age of 1.30 Billion of Years but could be as young as 1.10 to 1.50 according to Hipparcos.

HIP35487 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD57167.

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

Location of R 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 R Canis Majoris, the location is 07h 19m 28.08 and -16d23`41.7 .

Proper Motion of R 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 -136.18 ± 0.33 miliarcseconds/year towards the north and 165.37 ± 0.54 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Age, Radius) of R Canis Majoris

R Canis Majoris has a spectral type of F2III/IV. This means the star is a blue to white subgiant star. The star is 7427.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24224.1515588800000000s. The star has a B-V Colour Index of 0.34 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,016 Kelvin.

R Canis Majoris Radius has been calculated as being 2.02 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,403,409.21.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.96. 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 0.05 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

The stars age according to Hipparcos data files put the star at an age of about 1.30 Billion years old but could be between 1.10 and 1.50 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

R Canis Majoris Apparent and Absolute Magnitudes

R Canis Majoris has an apparent magnitude of 5.70 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 2.48 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.54. 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 R Canis Majoris

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 22.71 which gave the calculated distance to R Canis Majoris as 143.62 light years away from Earth or 44.03 parsecs. It would take a spaceship travelling at the speed of light, 143.62 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 23.38 which put R Canis Majoris at a distance of 139.51 light years or 42.77 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 7,427.00 Parsecs or 24,224.15 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 R Canis Majoris

The star is a eclipsing Beta Persei (Algol)/Semi-Detached System (subtype) 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. R Canis Majoris brightness ranges from a magnitude of 6.417 to a magnitude of 5.780 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 1.1 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.

R Canis Majoris Facts

Alternative Names

Traditional/Proper NameR Canis Majoris
Short NameR CMa
Hipparcos Library I.D.35487
Bonner DurchmusterungBD-16 1898
Henry Draper Designation57167

Visual Facts

Star Typesubgiant star
Age1.30 Billion Years Old
Age Range1.10 - 1.50 Billion Years Old
Absolute Magnitude2.48 / 2.54
Visual / Apparent Magnitude5.70
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)07h 19m 28.08
Declination (Dec.)-16d23`41.7
Galactic Latitude-1.41 degrees
Galactic Longitude230.67 degrees
1997 Distance from Earth22.71 Parallax (milliarcseconds)
 143.62 Light Years
 44.03 Parsecs
2007 Revised Distance from Earth23.38 Parallax (milliarcseconds)
 139.51 Light Years
 42.77 Parsecs
Galacto-Centric Distance24,224.15 Light Years / 7,427.00 Parsecs
Proper Motion Dec.-136.18 ± 0.33 milliarcseconds/year
Proper Motion RA.165.37 ± 0.54 milliarcseconds/year
B-V Index0.34
Radial Velocity-32.70 ± 2.90 km/s
Iron Abundance0.05 ± 9.99 Fe/H
Spectral TypeF2III/IV
Colour(F) blue to white

Variable Star Details

Variable Star ClassEclipsing
Variable Star TypeBeta Persei (Algol)/Semi-Detached System (subtype)
Mean Variability Period in Days1.136
Variable Magnitude Range (Brighter - Dimmer)5.780 - 6.417

Estimated Facts

Calculated Effective Temperature7,016 Kelvin

Sources and Links

SIMBAD SourceLink

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