A new planet has been found orbiting our nearest star system, Alpha Centauri. It is a discovery that pushed the used technology to the limit and though likely not supporting life, it gives hope that other planets may be nearby.
The Alpha Centauri system is a binary star system, and at an approximate 4.5 light years away, it is also the closest star system to earth. The two stars orbit each other with an orbit of approximately 80 earth years. It was recently discovered that a hitherto unknown planet is orbiting one of the system's stars, Alpha Centauri B, thus making it the closest exoplanet known to mankind.
The planet was found by a research team under Xavier Dumusque of Geneva Observatory and University of Porto in Portugal, who made the discovery by utilizing an instrument called the High Accuracy Radial velocity Planet Searcher, (HARPS). The techniques used looked at tiny wobbles in Alpha Centauri B: Gravitational interaction between the star and the planet pulls both the planet towards the star, and the other way around. By observing the star's position, one can determine if there's a planet in the system by how much the star is moving, wobbling, as the planet circles it.
Artist's rendering of Alpha Centauri Bb
In this case, the star was wobbling at a speed of 1.8 kph, making it very difficult to detect. It took more than 4 years and 450 HARPS observations to confirm the existence of the planet.
"It’s an extraordinary discovery, and it has pushed our technique to the limit," said Dumusque in a statement.
The study is being published today in the journal Nature, despite the fact that some scientists are still debating the existence of the planet. Researchers cite the extremely weak signal as a potential for error. Dumusque's team however, state that the probability of having a false reading according to their tests, is 0.1%
The planet, known as Alpha Centauri Bb, is a super earth, a rocky planet with approximately 113% the mass of the earth. Whenever one hears of an exoplanet, hopes of finding alien life, or perhaps the prospect of colonizing it, come to mind. However, chances are slim for either of those, as it is outside the star's habitable zone, much too close to the sun and likely filled with molten rock and lava. Alpha Centauri Bb is in fact, very close to it's star at just 6 million kilometers. Earth, to compare, is roughly 150 million kilometers from the sun. Due to Bb's close proximity to it´s sun, it also orbits very quickly; a year on Bb is just 3.2 days long
Luckily, the heat doesn't mean that the discovery is negligible; the existence of one exoplanet often means the existence of more in a system; it is common for solar systems with low mass planets (such as Bb) to have somewhere between two and seven planets. Perhaps farther out in the system, in the habitable zone where liquid water can be present, there is hope for another planet.