Hi Guys

Here's an updated article at the physics preprints archive...

http://arxiv.org/astro-ph/0107482

Serge Tabachnik and Scott Tremaine have done an analysis of the probability distribution of the exosolar planets and found:

a) 3.3% of stars have Jupiter mass or larger planets [1Mj < M < 10Mj] with orbital periods between 6 days and 10 years.

b) extrapolating they find planets with periods between 2 days & 5 years number about 0.28 of those between 5 years & 1000 years. Which suggests about ~ 10% in all will have them. That's consistent with microlensing surveys that have found 1/3 or less have Jovians.

c) extrapolating for earth-like planets, they find that about 15 % of stars will have earth-sized planets or larger.

d) they find evidence for a separate formation mechanism for brown dwarf stars, as the planets tail off in mass rapidly after 10 Mj.

I've read another study [and forgot the reference, sorry] which suggests that highly eccentric orbits are a feature of the near-in Jovians, while beyond ~ 2 AU most will have near circular orbits. Out past 3 - 4 AU I'd suggest the systems will be candidates for terrestrial planets in stable orbits.

Hopefully a large scale survey program, like Kepler, will tell us more by 2010.

Adam