Tom quotes:

>Stars abundant in heavy metals are five times more likely to have a planetary
>companion than metal-poor stars, Fischer said.

If we understand what happened during the Big Bang -- and the evidence suggests
that it appears that we do -- and if we understand how planets are formed, then
that statement is a bit of a tautology.

Astronomers consider any element heavier than hydrogen to be a "metal,"
although you sometimes hear some definitional creep in that statement. Helium
and lithium are sometimes included nowadays in the non-metal category. Hydrogen
was the only element primarily formed during the Big Bang, although some
helium, helium-3, lithium and deterium was also created. There was insufficient
energy in the Big Bang to form anything heavier, thus any element that we find
in the universe heavier than these few nuclei we can be sure was formed in the
fusion furnaces of stars. See:

http://physics.weber.edu/carroll/Wonder/big_bang_nucleosynthesis.htm

It is commonly believed that planets, even gas giants, cannot form without a
rocky core, thus the presence of "metals" formed in
previous-generation stellar
cores is critical to the planet-forming process. The gases hydrogen and helium
are not believe to be capable of condensing on their own into a planet-like
structure. As the metallicity of a system rises (due primarily to the central
star being a second- or third-generation star), the likelihood that bodies that
we would call planets will form increases.

Wirt Atmar
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