Universe Guide

Proxima Centauri (Alpha Centauri C) Star Facts

Proxima Centauri Facts

  • Proxima Centauri is a main sequence star that can be located in the constellation of Centaurus. The description is based on the spectral class.
  • Proxima Centauri is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (M5Ve) of the star, the star's colour is red .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • Proxima Centauri has at least 1 Extrasolar Planets believed to be in orbit around the star.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 4.23 light years away from us. Distance

Information on Proxima Centauri

Proxima Centauri is the closest star to the Earth after the Sun. It is a small red dwarf and as such, it lay undiscovered in the heavens. It is a faint star, one that is not possible to see with the naked eye.

Red Dwarf stars are the most efficient stars in the Universe, they convert hydrogen into helium at a very slow rate compared to giant stars such as Betelgeuse for example. A red dwarf star will live longer than most other other stars due to the way it uses its fuel reserves. Long after the Sun has died, Proxima Centauri will still be alive, continuing to convert hydrogen into helium.

In addition to be the second closest star at a mere 4 light years away, it is also the nearest star with an extrasolar planet in orbit. The bad news is that the planet is constantly being flamed by its star and therefore you can rule out there being any life on the planet.

Proxima Centauri's Alternative Names

(Alpha Centauri C) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

HIP70890 is the reference name for the star in the Hipparcos Star Catalogue. The Gliese ID of the star is GL 551. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

Proxima Centauri has alternative name(s) :- , Proxima Cen.

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

Location of Proxima Centauri

The location of the main sequence 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 object is compared to the celestial equator and is expressed in degrees. For Proxima Centauri, the location is 14h 29m 47.75 and -62° 40` 52.9 .

Radial Velocity and Proper Motion of Proxima Centauri

Proper Motion

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 ± 1.57 milliarcseconds/year towards the north and -3,775.75 ± 2.60 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -22.40000 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.

Physical Properties of Proxima Centauri

Proxima Centauri Colour and Temperature

Based on the star's spectral type of M5Ve , Proxima Centauri's colour and type is red main sequence star. The star has a B-V Colour Index of 1.8 which means the star's temperature is about 2,942 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Proxima Centauri Radius

Proxima Centauri estimated radius has been calculated as being 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. 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 0.0293404308070473090132631306. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

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 772.33000 which gave the calculated distance to Proxima Centauri as 4.22 light years away from Earth or 1.29 parsecs. If you want that in miles, it is about 24,807,799,074,834.83, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 771.64000 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.

Using the 2007 distance, the star is roughly 268,142.38 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 7,399.00 Parsecs or 24,132.83 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Proxima Centauri

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A3807363,854,223.29
Speed of Sound (Mach 1)767.2693,697,149.68
Concorde (Mach 2)1,534.541,848,572.43
New Horizons Probe33,00085,960.86
Speed of Light670,616,629.004.23

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.

Hide Explanations
Show GridLines

Additional Proxima Centauri Facts and Figures

Visual Facts

Primary / Proper / Traditional NameProxima Centauri
Alternative NamesAlpha Centauri C, HIP 70890, Gliese 551, Proxima Cen
Spectral TypeM5Ve
Constellation's Main StarNo
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
GalaxyMilky Way
Absolute Magnitude 15.46 / 15.44
Visual / Apparent Magnitude11.01
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)14h 29m 47.75
Declination (Dec.)-62° 40` 52.9
Galactic Latitude-1.93227672 degrees
Galactic Longitude313.94769909 degrees
1997 Distance from Earth772.33000 Parallax (milliarcseconds)
 4.22 Light Years
 1.29 Parsecs
2007 Distance from Earth771.64000 Parallax (milliarcseconds)
 4.23 Light Years
  1.30 Parsecs
 268,142.38 Astronomical Units
Galacto-Centric Distance24,132.83 Light Years / 7,399.00 Parsecs
Proper Motion Dec.765.54000 ± 1.57000 milliarcseconds/year
Proper Motion RA.-3775.75000 ± 2.60000 milliarcseconds/year
B-V Index1.8
Radial Velocity-22.40000 ± 0.50 km/s
Semi-Major Axis8852.0000000
Associated / Clustered StarsRigil Kentaurus

Companions (Multi-Star and Exoplanets) Facts

Exoplanet Count1

Estimated Calculated Facts

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

Sources and Links

SIMBAD SourceLink

Location of Proxima Centauri in Centaurus

Proxima Centauri Location in Centaurus

The map was generated using Night Vision, an awesome free application by Brian Simpson.

List of Extrasolar Planets orbiting Proxima Centauri

NameStatusMass (Jupiters)Orbital Period (Days)EccentricityDiscoveredSemi-Major AxisPeriastron
Proxima Centauri bConfirmed0.000611.1860.020160.0485

Related Stars

Proxima Centauri Solar System

This is a N.A.S.A. impression of what the solar system might look like. If the star is not on display, its because its so small compared to the orbits of the outer planets. The green area denotes the habital zone which if the planet is within that area, life could exist. The habital zone might not appear on the picture because its outside the area for the picture. Our planets show the orbit of the planet if its was in our solar system. For more information about the planet and other exoplanetary stuff, visit N.A.S.A.

Proxima Centauri Solar System

Comments and Questions

There's no register feature and no need to give an email address if you don't need to. All messages will be reviewed before being displayed. Comments may be merged or altered slightly such as if an email address is given in the main body of the comment.

You can decline to give a name which if that is the case, the comment will be attributed to a random star. A name is preferred even if its a random made up one by yourself.

This website is using cookies. More info. That's Fine