New Planet found in the nearest star system to Earth!

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Just last month, European astronomers have discovered an exoplanet the size of Earth orbiting a star within the Alpha Centauri system - The closest star system to Earth!

 

The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile, and is the lightest exoplanet ever found to be orbiting a sun like star.

 

Alpha Centauri is one of the brightest, most visible stars in the southern skies, and our closest neighbouring system, around 4.3 light years away. The Alpha Centauri system is actually a triple system - that is a system with 3 stars. There is two stars, Alpha Centauri A, and Alpha Centauri B, which are both sun-like stars (A sun-like star is a star with a similar mass, and therefore life cycle, to our Sun) orbiting eachother in close proximity, alongside a more distanct, and fainter component, Proxima Centauri. Since the 19th Centurty, astronomers have discussed the possibilities of life harbouring planets in this system, as it is the closest possible abode for life to our star. However, searches of increasing precision has not revealed anything, until now.

 

“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days,” says Xavier Dumusque (Geneva Observatory, Switzerland and Centro de Astrofisica da Universidade do Porto, Portugal), lead author of the paper. “It’s an extraordinary discovery and it has pushed our technique to the limit!”

The planet was detected by observing miniscule wobbles in the motion of Alpha Centauri B, movements of around 51cm per second. (This translates to about 1.8km/s, around the speed a baby crawls around). To us, this may seem a fair amount of movement, but on the scale of a star? It's almost completely insignificant!

As you may have already guessed, an orbital period of 3.2 days suggests an incredibly close proximity between the object and the star (according to the laws of circular motion) and so it will be too dry and too hot to have any chance of harbouring life as we know it. But that's not quite the point. This planet may be the equivilent to our Mercury, and the first planet in a system of several. Previous results from HARPS indicate that the majority of low mass planets i.e. Earth-Sized planets, are found in such systems. So there's hope of extra terrestrial life in the immediate vicinity of our own Solar System!

Source: ESO (European Space Observatory) http://www.eso.org/public/