Universe Guide


Proxima Centauri (Alpha Centauri C) - HIP70890

Proxima Centauri (Alpha Centauri C) is a red main sequence dwarf star that can be located in the constellation of Centaurus. Alpha Centauri C is the Bayer Classification for the star. HIP70890 is the reference name for the star in the Hipparcos Star Catalogue.

Location of Proxima Centauri

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 Proxima Centauri, the location is 14h 29m 47.75 and -62d40`52.9 .

Proper Motion of Proxima Centauri

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 765.54 ± 001.57 towards the north and -3,775.75 ± 002.60 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Proxima Centauri

Proxima Centauri has a spectral type of M5Ve. This means the star is a red main sequence dwarf star. The star has a B-V Colour Index of 1.8 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 2,942 Kelvin.

Proxima Centauri has been calculated as 0.03 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 20,227.90.km.

The star has companion stars which are in orbit close by, it has at least the following companions in close orbit, Rigil Kentaurus, Alpha Centauri B.

Proxima Centauri Apparent and Absolute Magnitudes

Proxima Centauri has an apparent magnitude of 11.01 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 15.46 If you used the 2007 Parallax value, you would get an absolute magnitude of 15.44. 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 Proxima Centauri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 772.33 which gave the calculated distance to Proxima Centauri as 4.22 light years away from Earth or 1.29 parsecs. It would take a spaceship travelling at the speed of light, 4.22 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 771.64 which put Proxima Centauri at a distance of 4.23 light years or 1.30 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.

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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Proxima Centauri Facts

Alternative Names

Traditional NameProxima Centauri
Bayer DesignationAlpha Centauri C
Hipparcos Library I.D.70890

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude15.46 / 15.44
Apparent Magnitude11.01
Right Ascension (R.A.)14h 29m 47.75
Declination (Dec.)-62d40`52.9
1997 Distance from Earth772.33 Parallax (milliarcseconds)
 4.22 Light Years
 1.29 Parsecs
2007 Revised Distance from Earth771.64 Parallax (milliarcseconds)
 4.23 Light Years
 1.30 Parsecs
Proper Motion Dec.765.54 ± 1.57 milliarcseconds/year
Proper Motion RA.-3775.75 ± 2.60 milliarcseconds/year
B-V Index1.80
Spectral TypeM5Ve
Colour(M) Red

Companions (Multi-Star and Exoplanets) Facts

Companion StarsRigil Kentaurus
Alpha Centauri B

Estimated Facts

Radius (x the Sun)0.03
Calculated Effective Temperature2,942 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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