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Canopus, Alpha Carinae, HD45348, HIP30438, HR2326

Canopus Location in Carina

Primary Facts on Canopus

  • Canopus's star type is supergiant star that can be located in the constellation of Carina. The description is based on the spectral class.
  • Canopus is a main star of the constellation outline.
  • Based on the spectral type (F0Ib) of the star, the star's colour is blue to white .
  • Alpha Carinae is the Bayer name for the star. It was assigned this name by Johann Bayer in 1603. The closer to the start of the Greek Alphabet the name, the brighter the star is. Alpha stars tend to be the brightest in the constellation. A notable exception is Pollux (Beta Geminorum) which is the brighest star in the Gemini constellation.
  • Canopus is the 2nd brightest star in the night sky and is the brightest star in Carina 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.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 309.16 light years away from us.

Canopus's Alternative Names

Alpha Carinae (Alf Car) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR2326. HIP30438 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD45348.

More details on star alternative names can be found at Star Names .

Location of Canopus

The location of the star in the night sky 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 Canopus, the location is 06h 23m 57.09 and -52° 41` 44.6 .

Radial Velocity and Proper Motion of Canopus

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 23.24 ± 0.53 miliarcseconds/year towards the north and 19.93 ± 0.56 miliarcseconds/year east if we saw them in the horizon.

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 20.30 km/s with an error of about 0.50 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Canopus 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 13,187.52 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of Canopus

Canopus has a spectral type of F0Ib. This means the star is a blue to white supergiant star. The star is 7,414.00 Parsecs from the Galactic Centre or in terms of Light Years is 24,181.75 s. The star has a B-V Colour Index of 0.16 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,747 Kelvin.

Canopus Radius has been calculated as being 66.17 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 46,044,208.22.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 65.27. 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 -0.11 with an error value of 0.03 Fe/H with the Sun has a value of 1 to put it into context.

Canopus Apparent and Absolute Magnitudes

Canopus has an apparent magnitude of -0.62 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 -5.53 If you used the 2007 Parallax value, you would get an absolute magnitude of -5.50. 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 Canopus

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 10.43 which gave the calculated distance to Canopus as 312.72 light years away from Earth or 95.88 parsecs. It would take a spaceship travelling at the speed of light, 312.72 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 10.55 which put Canopus at a distance of 309.16 light years or 94.79 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.

Using the 2007 distance, the star is roughly 19,551,704.75 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

The star's Galacto-Centric Distance is 7,414.00 Parsecs or 24,181.75 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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.

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Additional Canopus Facts and Figures

Visual Facts

Primary / Proper / Traditional NameCanopus
Alternative NamesAlpha Carinae, Alf Car, HD 45348, HIP 30438, HR 2326
Spectral TypeF0Ib
Constellation's Main StarYes
Multiple Star SystemNo / Unknown
Star Type very luminous Supergiant Star
Colour blue to white
GalaxyMilky Way
Absolute Magnitude -5.53 / -5.50
Visual / Apparent Magnitude-0.62
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)06h 23m 57.09
Declination (Dec.)-52° 41` 44.6
Galactic Latitude-25.29 degrees
Galactic Longitude261.21 degrees
1997 Distance from Earth10.43 Parallax (milliarcseconds)
 312.72 Light Years
 95.88 Parsecs
2007 Distance from Earth10.55 Parallax (milliarcseconds)
 309.16 Light Years
 94.79 Parsecs
 19,551,704.75 Astronomical Units
Galacto-Centric Distance24,181.75 Light Years / 7,414.00 Parsecs
Proper Motion Dec. 23.24 ± 0.53 milliarcseconds/year
Proper Motion RA.19.93 ± 0.56 milliarcseconds/year
B-V Index0.16
Radial Velocity20.30 ± 0.50 km/s
Iron Abundance-0.11 ± 0.03 Fe/H
Semi-Major Axis6972.00
Stellar Luminosity (Lsun)13,187.52
Brightest in Night Sky2nd

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Facts

Calculated Effective Temperature7,747 Kelvin

Sources and Links

SIMBAD SourceLink

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