Human Scientists Discover Earth Sized Planet at Alpha Cent.

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Human Scientists Discover Earth Sized Planet at Alpha Cent.

Postby RaharuAharu » Wed Oct 17, 2012 4:46 am

http://io9.com/5952357/scientists-discover-a-planet-in-alpha-centauri-the-star-system-nearest-earth

This is huge. We've discovered a lot of exoplanets, including rocky Earth-like ones, in far-away star systems. But the European Space Agency announced this afternoon that our solar system's nearest neighbor, a brilliant trinary star system called Alpha Centauri, has a planet that's roughly the mass of Earth. That's right — just 4.3 light years away, there's a planet that might be a lot like our own.

Well, it might be like our own in terms of its mass, which is quite similar to Earth's. But this planet has a year that's just a little over three days long, which means it's orbiting really close to its sun. The place is likely a superheated ultra-Mercury. Reports the ESA:

European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system - the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO's La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.

Alpha Centauri is one of the brightest stars in the southern skies and is the nearest stellar system to our Solar System - only 4.3 light-years away. It is actually a triple star - a system consisting of two stars similar to the Sun orbiting close to each other, designated Alpha Centauri A and B, and a more distant and faint red component known as Proxima Centauri. Since the nineteenth century astronomers have speculated about planets orbiting these bodies, the closest possible abodes for life beyond the Solar System, but searches of increasing precision had revealed nothing. Until now.

Not only is this a big deal symbolically — there's a planet practically next door! — but it's also a huge breakthrough scientifically. Over at Bad Astronomy, Phil Plait explains:

The reason this is a big deal is twofold. For one, Alpha Cen is the closest star system in the sky. Because of that it's very bright, and well studied. Planets searches have looked there for decades, and in fact for a while it was thought the dinky red dwarf Proxima might have a planet. Those earlier findings have been shown to be wrong, though. If it has a planet, it's too small or too far out from the star (or both) to detect it easily.

The other reason this is important is that the signal from the planet is incredibly weak. It was found through its gravity. As it orbits Alpha Cen B, the planet tugs on the star, like two children holding hands and swinging each other around. This sets up a very small but detectable Doppler shift in the starlight. The more massive the planet is, the harder it tugs on the star, and the bigger the signal (making it easier to detect). Also, the closer in a planet is, the larger the signal is… and you get the added benefit of a short orbital period, so you don't have to observe as long to see the cycle of the Doppler shift.

In this case, the planet is low mass but very close in. The Doppler shift in the starlight amounts to a mere half meter per second – slower than walking speed! When I read that I was stunned; that low of a signal is incredibly hard to detect.
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Re: Human Scientists Discover Earth Sized Planet at Alpha Ce

Postby RaharuAharu » Wed Oct 17, 2012 4:48 am

Theres more

http://www.eso.org/public/news/eso1241/

European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system — the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.

Alpha Centauri is one of the brightest stars in the southern skies and is the nearest stellar system to our Solar System — only 4.3 light-years away. It is actually a triple star — a system consisting of two stars similar to the Sun orbiting close to each other, designated Alpha Centauri A and B, and a more distant and faint red component known as Proxima Centauri [1]. Since the nineteenth century astronomers have speculated about planets orbiting these bodies, the closest possible abodes for life beyond the Solar System, but searches of increasing precision had revealed nothing. 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 European team detected the planet by picking up the tiny wobbles in the motion of the star Alpha Centauri B created by the gravitational pull of the orbiting planet [2]. The effect is minute — it causes the star to move back and forth by no more than 51 centimetres per second (1.8 km/hour), about the speed of a baby crawling. This is the highest precision ever achieved using this method.

Alpha Centauri B is very similar to the Sun but slightly smaller and less bright. The newly discovered planet, with a mass of a little more than that of the Earth [3], is orbiting about six million kilometres away from the star, much closer than Mercury is to the Sun in the Solar System. The orbit of the other bright component of the double star, Alpha Centauri A, keeps it hundreds of times further away, but it would still be a very brilliant object in the planet’s skies.

The first exoplanet around a Sun-like star was found by the same team back in 1995 and since then there have been more than 800 confirmed discoveries, but most are much bigger than the Earth, and many are as big as Jupiter [4]. The challenge astronomers now face is to detect and characterise a planet of mass comparable to the Earth that is orbiting in the habitable zone [5] around another star. The first step has now been taken [6].

“This is the first planet with a mass similar to Earth ever found around a star like the Sun. Its orbit is very close to its star and it must be much too hot for life as we know it,” adds Stéphane Udry (Geneva Observatory), a co-author of the paper and member of the team, “but it may well be just one planet in a system of several. Our other HARPS results, and new findings from Kepler, both show clearly that the majority of low-mass planets are found in such systems.”

“This result represents a major step towards the detection of a twin Earth in the immediate vicinity of the Sun. We live in exciting times!” concludes Xavier Dumusque.

ESO will hold an online press conference offering journalists the opportunity to discuss the result and its impact with the scientists.
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Re: Human Scientists Discover Earth Sized Planet at Alpha Ce

Postby Wizard CaT » Thu Dec 06, 2012 6:57 pm

Cool. Though we all know this due to the prophetic game Alpha Centuri. urbs#3
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