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Fraser
2003-Jul-21, 05:39 PM
SUMMARY: A survey of stars in our neighbourhood has revealed those rich in metals, such as iron and titanium, are five times more likely to have planets orbiting them. The survey of 61 stars with planets and 693 stars without, revealed a distinct difference in the 'metalicity' of stars. Debra Fisher from the University of California, Berkley, says, "If you look at the metal-rich stars, 20 percent have planets. That's stunning."


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Ray Bauernhuber
2003-Jul-21, 11:32 PM
Can someone please explain to me in laymen's terms why planets are so attracted to metal rich stars? Thank you. :)

kashi
2003-Jul-22, 01:08 AM
I'm always unsure when I read these studies. When you consider just how limited a percentage of the observable universe the survey was conducted in, and how limited our planetary detection methods are (especially for Earth sized planets), one can't help but think that surveys such as this might not be the complete picture.

When we've discovered 10000 planetary systems let us conduct the survey again.

Ray,

It's not so much that they are attracted to such stars, but probably that in the protoplanetary disk stage of solar system formation (when a big cloud of tiny dust particles are rotating around the centre of gravity of the system), larger elements probably tend to "clump together" more easily, and thus eventually form planets. I think that's the idea anyway.

Kashi

Carl
2003-Jul-23, 07:50 AM
That pretty much sums it up Kashy. The hypothesis is that heavier elements stick together easier, allowing dust, rocks and eventually planetary cores to form around newly ignited stars.

This should be exciting news to SETI supporters. One problem with trying to find other life in the universe is knowing exactly where to look. One Australian Astronomer recently calculated the number of visible stars in the universe to be approximately some 70 sextillion, or 70 thousand million million million.

With so many possible abodes for life, where do you even begin to start listening for radio signals or other signs of intelligence. Distance is one deciding factor ofcourse. The greater the distance the harder it is to detect anything. However that still leaves a great number of stars in our region of the galaxy to look at.

Looking for what we suspect is necessary for carbon based life like ourselves is another way of reducing the available stars for close study. A lone G-type or similar classed star seems the most likely home for ET if he shares our love of liquid water and needs a stable star system to evolve. Now it seems we can further eliminate stars with low amounts of metal. This greatly improves our odds of finding interstellar neighbours as it narrows down the target stars to concentrate on and increases our odds of finding planets at those stars.
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