Alpha Centauri A (α Cen A)

By: Tanvi Kongara Period: 2



  • Relative to the Sun (Sun=1): 1.09
  • Alpha Centauri has a mass of about 109% greater than the Sun


  • Relative to the Sun (Sun=1): 1.2
  • Alpha Centauri has a radius of abut 22% larger than the Sun's

Color and Temperature

Color: Yellow

Temperature: 5800 K (Sun=5770 a


Definition: amount of energy released in a star due to nuclear fusion

Luminosity of Alpha Centauri A: 1.519 (Sun=1)

  • Alpha Centauri’s surface temperature is a few degrees Kelvin less than our sun but its diameter and the overall larger surface area gives it a luminosity nearly 1.6 times that of our star.

Absolute and Apparent Magnitude


  • Definition: the magnitude of a star if it was placed a distance of 10 parsecs/ 32.6 light years away from the Earth
  • Absolute magnitude of Alpha Centauri A : 4.34


  • Definition: how bright an object appears in the sky from Earth
  • Apparent Magnitude of Alpha Centauri A : -0.01

Light Years from Earth

Definition: distance that light travels in one year (about 5.88 trillion miles)

Alpha Centauri A distance from Earth: 4.37 light years

Spectral Classsification

The spectral classification for Alpha Centauri is G2, which is the same spectral classification as the our star, the Sun.

Age and Stellar Evolution Stage

Age: 4850 million years

Stellar Evolution Stage: Main Sequence

Star History

The binary nature of the Alpha Centauri system (Alpha Centauri A, Alpha Centauri B, and Proxima) was first recognized in December 1689 by astronomer Jean Richaud. The finding was made accidentally while observing a passing comet from his station

Binary System

Alpha Centauri A is part of the Alpha Centauri System : Alpha Centauri A, Alpha Centauri B, and Proxima (Red Dwarf). The Alpha Centauri system can be classified as a triple star system.
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Interesting Facts

1. Alpha Centauri A is the 4th brightest star seen from Earth and the brightest star seen from the Southern Hemisphere

2. Alpha Centauri is almost never seen in the Northern Hemisphere and it is said to never set in the Southern Hemisphere

3. Alpha Centauri A is part of a constellation - Centaurus

4. This star and its system has been mentioned in many books and film; some of the most prominent include Avatar, Lost in Space, Transformers, and most commonly known Star Trek