Hi All

No, I am not selling interstellar real estate sight-unseen... though I have a few coming on market soon ;-)

Geoff Marcy, Paul Butler and co. have e-printed a new piece that summarises current findings and extrapolates trends from current data. Some eye-openers...

(1) Just 12% of sun-like (FGK) stars have Jovian planets within 20 AU based on extrapolation from discovery rates and so forth.

(2) Probability varies with metallicity - from <3% of stars for low (<1/3 Solar) to ~ 25% for high metallicity stars (>3 solar)

(3) All the hot Jupiters around stars in the sample star set are now found.

(4) Eccentricity remains >0.25 on average even for long-period Jovians, so our rather peaceful Big planets are definitely looking odd.

Another good discussion is on the effectiveness of just using the Terrestrial Planet Finder (TPF) on its own - it's unlikely to succeed without pre-screening the stars with the Space Interferometry Mission (SIM) plus statistical guidance on planet occurance from Kepler. Also to find 1 Earth Mass planets SIM will need to run longer than 5 years or else it will miss them.

Astrophysics, abstract
astro-ph/0505003
From: Geoffrey W. Marcy [view email]
Date: Fri, 29 Apr 2005 23:38:45 GMT (282kb)

Observed Properties of Exoplanets: Masses, Orbits, and Metallicities
Authors: G.Marcy, R.P.Butler, D.A.Fischer, S.S.Vogt, J.T.Wright, C. G. Tinney, H. R.A. Jones
Comments: Nishinomiya-Yukawa Symposium

We review the observed properties of exoplanets found by the Doppler technique which has revealed 152 exoplanets to date. We focus on our ongoing 18-year survey of 1330 FGKM type stars at Lick, Keck, and the Anglo-Australian Telescopes carried out with a uniform Doppler precision of 3 m/s. The 104 planets detected in our survey have masses as low as 15 M_Earth orbiting between 0.03 and 5.5 AU. The mass distribution rises toward the lowest detectable masses as dN/dM \propto M^-1.1. Nearly all giant planets orbiting within 2 AU of all FGK stars within 30 pc have now been discovered. The distribution of semi-major axes rises from 0.3 -- 3.0 AU (in bins of Delta log a), but remains unknown for larger orbits. Extrapolation suggests that 12% of the FGK stars harbor exoplanets within 20 AU. The median orbital eccentricity is <e>=0.25 (excluding those tidally circularized), lower than previously measured . Planets orbiting beyond 3 AU continue to exhibit non-zero eccentricity, suggesting that the circular orbits of giant planets in our Solar System are unusual. The occurrence rate of ``hot Jupiters'' within 0.1 AU is 1.2$\pm$0.3 %. The probability of occurrence of planets varies as the square of the stellar metal abundance, $P \propto N^2_Fe, ranging from $<$3% for stars of subsolar metallicity to 25% for stars with [Fe/H] > +0.3. Nearly 14% of planet-bearing stars harbor multiple-planet systems, occasionally locked in resonances. Kepler and Corot should measure the occurrence of earth-sized planets. The Space Interferometry Mission (SIM) will detect planets with masses as low as 3 M_ Earth orbiting within 2 AU of nearby stars and will measure masses, orbits and multiplicity. These candidate rocky planets will motivate spectroscopic follow-up by the ``Terrestrial Planet Finder'' and Darwin.}