Five best stars for Intelligent extraterrestial life

Margaret Turnbull, an astronomer at the Carnegie Institution in Washington DC has winnowed down her list of 17,000 stellar systems that might be inhabited to the five best possibilities. BBC has the story.

Besides being most likely to hold intelligent life, these stellar systems are also the five best choices for us to move to if our current solar system becomes uninhabitable. The key is that they are the most like the system we currently live in.

These stars were chosen because they:

• are at least 3 billion years old.
• have at least 50% the iron content of our sun.
• have no companion star.
• are no more than 1.5 times the size of our sun.
  
• are not variable stars with a lot of solar flares as these tend to be too young.
  

The five best candidate stars are:

• Beta CVn: a sun-like star 26 light-years away in the constellation Canes Venatici (the hound dogs)
• HD 10307: has almost the same mass, temperature and iron content of the Sun
• HD 211 415: has about half the metal content of the Sun and is a bit cooler
• 18 Sco: a near match for the Sun in the constellation Scorpio
• 51 Pegasus: a Jupiter-like planet has been found here, may also host planets like Earth

So, my question is - if Beta CVn is only 26 light-years away and is so much like our system that it might also have intelligent life, why have we not identified radio waves from there yet? Twenty-six years for light (thus radio or tv signals) to get from here to there. They've been able to watch "I Love Lucy," "The honeymooners," "Gilligan's Island," "The A Team," and even "The Rockford Files." Why haven't we seen their radio waves? Don't they have culture also?

Is intelligence that rare?

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Addendum Feb 20, 2006
A more detailed article cam be found in The Independent.