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Alpha Centauri Has an Earth-Sized Planet
The Bad Astronomer writes "Astronomers have announced that the nearest star system in the sky — Alpha Centauri — has an Earth-sized planet orbiting one of its stars. Alpha Cen is technically a three-star system: a binary composed of two stars very much like the Sun, orbited by a third, a red dwarf, much farther out. Using the Doppler technique (looking for very small changes in the velocities of the stars) astronomers detected a planet orbiting the smaller of the two stars in the binary, Alpha Centauri B. The planet has a mass only 1.13 times that of the Earth, making it one of the smallest yet detected.However, it orbits the star only 6 million kilometers out, so it's far too hot to be habitable. The signal from the planet is extremely weak but solidly detected (PDF), giving astronomers even greater hope of being able to find an Earth-like planet orbiting a star in its habitable zone."
The stars are actually very wide spaced compared to the planet-star system itself. As a result, the planet is well within the gravity well of B. At a minimum AB separation is 11AU - well over 200 times the B-planet separation.
Orbit centred on A: https://upload.wikimedia.org/wikipedia/commons/e/ee/Orbit_Alpha_Centauri_AB_arcsec.png
Simulation plus table of info: http://www.solstation.com/orbits/ac-absys.htm
Not unfortunate, just a recognition of reality. At this moment in time, the science return for sending unmanned probes / orbiters / rovers vastly exceeds the return on sending humans. We'll continue to develop space capability and at some point it may make sense to send humans to Mars ... or maybe not.
And please do NOT invoke the whole "omg we have to get off this rock" argument. If an asteroid impact blew most of Earth's atmosphere and water into space and annihilated 99.999% of the species, Earth would STILL be easier to live on than Mars.
It'll get ejected - that configuration isn't stable.
For Alpha Centauri A and B, the 'stable zone' is out to roughly Jupiter's orbit from each star - plenty of room for both to have habitable worlds.
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