New planets around local star

23 December 2012
Posted by Chris Smith.

One of the traditional things to think about around christmas is of course stars, and this week it has been announced that one of our local stars, Tau Ceti, is not alone as we once thought.

Tau Ceti is the closest start to earth which is similar to the sun, it is about 3/4 as massive, and about half as bright, but it is yellow and otherwise very similar, and just under 12 light years from us. 

An international team of astronomers including Mikko Tuomi from the university of Hertfordshire thought this proximity and similarity to the sun and its apparent lack of planets was going to be useful to calibrate a technique looking at minute changes in the wavelength of light given off by the star caused by the star wobbling due to the influence of a planet.

They wanted to understand the noise in their data better enabling them to detect smaller planets than ever before, so they looked at Tau Ceti which shouldn't have had any planets, they were then going to add pretend planet signals to the data and see if they could detect them.

While they were doing this they noticed that they were getting signals even before they added the pretend ones in, Tau Ceti had planets, in fact at least 5 of them, and one of them which has about 5 times the mass of earth is orbiting in the habitable zone, where water is liquid.

This is particularly interesting because whilst we have discovered many exo-planets and several in the habitable zone, none have been this light, and none have been this close to earth. So when a telescope is built that is good enough to see light directly from an exoplanet, you can be sure that it will be pointing at Tau Ceti very early on, and it will be fascinating to find out what it discovers.

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