The Hubble Space Telescope team has released an incredible new image of the binary star Alpha Centauri AB.
This Hubble WFPC2 image shows Alpha Centauri A (left) and Alpha Centauri B (right). Image credit: NASA / ESA / Hubble.
Alpha Centauri, the closest stellar system to Earth, is located in the constellation of Centaurus.
Also known as Rigil Kentaurus, Rigil Kent and Gliese 559, this triple system is made up of the bright binary star formed by Alpha Centauri A and Alpha Centauri B, plus the faint red dwarf star Alpha Centauri C.
The two brighter components are roughly 4.35 light years away from us. Alpha Centauri C, better known as Proxima Centauri, is slightly closer at 4.23 light years.
Compared to the Sun, Alpha Centauri A is of the same stellar type G2, and slightly bigger (1.1 times more massive than the Sun and about 1.5 times more luminous).
Alpha Centauri B, a K1-type star, is slightly smaller and less bright (0.9 times the mass of the Sun and about 45% of its visual luminosity).
Alpha Centauri A and B orbit a common center of gravity once every 80 years, with a minimum distance of about 11 times the distance between the Earth and the Sun.
Because these two stars are, together with Proxima Centauri, our nearest interstellar neighbors, they are among the best studied by astronomers.
And they are also among the prime targets in the hunt for potentially habitable planets.
Using the HARPS instrument on the 3.6-m telescope at ESO’s La Silla Observatory, Chile, astronomers already discovered a planet orbiting Alpha Centauri B. The planet, designated Alpha Centauri Bb, has a mass of a little more than that of the Earth and orbits its host star once every 3.2 days.
Earlier this month, astronomers announced the discovery of an Earth-mass planet in the habitable zone orbiting Proxima Centauri. Named Proxima b, the planet orbits its star every 11 days and has a temperature suitable for liquid water to exist on its surface.
This image of Alpha Centauri AB is a composite of separate exposures acquired by Hubble’s Wide Field and Planetary Camera 2 (WFPC2).
It is based on data obtained through two filters: F457W and F850W.
The color results from assigning different hues to each monochromatic image associated with an individual filter.
