http://www.nasa.gov/mission_pages/spitzer/...r-20070329.html

Very interesting. One of the illustrations in that article (the dust ring round the close binary) bears an uncanny resemblance to a watercolour painting I did in the 1970s. I'll try to take a digital pic (tricky because it's behind glass) and post here if successful.

A look at planetary frequencies in binary systems from another angle. They conclude that there is no statistical difference in planet frequencies between single stars and (long-period) binary systems.

http://xxx.lanl.gov/abs/astro-ph/0703754

The frequency of planets in multiple systems
M. Bonavita, S. Desidera

The frequency of planets in binaries is an important issue in the field of extrasolar planet studies, because of its relevance in estimating of the global planet population of our Galaxy and the clues it can give to our understanding of planet formation and evolution. However, only preliminary estimates are available in the literature. We analyze and compare the frequency of planets in multiple systems to the frequency of planets orbiting single stars. We also try to highlight possible connections between the frequency of planets and the orbital parameters of the binaries (such as the periastron and mass ratio.) A literature search was performed for binaries and multiple systems among the stars of the sample with uniform planet detectability defined by Fischer & Valenti (2005), and 202 of the 850 stars of the sample turned out to be binaries, allowing a statistical comparison of the frequency of planets in binaries and single stars and a study of the run of the planet frequency as a function of the binary separation. We found that the global frequency of planets in the binaries of the sample is not statistically different from that of planets in single stars. Even conservatively taking the probable incompleteness of binary detection in our sample into account, we estimate that the frequency of planets in binaries can be no more than a factor of three lower than that of planets in single stars. There is no significant dependence of planet frequency on the binary separation, except for a lower value of frequency for close binaries. However, this is probably not as low as required to explain the presence of planets in close binaries only as the result of modifications of the binary orbit after the planet formation.

Bill

There has been a general assumption for decades in hard science fiction that planets would be possible in systems with very close and very distant binaries. Modeling at an arm-waving level said that Jupiter's moons would be equivalent to terrestrial planets or large asteroids orbiting a red dward at a distance from a larger star, etc.

There seemed to be more skepticism in astronomical circles, but till they started finding and doing detailed models of extra-solar systems, there was little real effort on modeling alternate solar systems... just models of solar-system-like-systems.

When they started finding hot jupiters and uber-eccentric-orbit planets, all bets were off on what seemed "reasonable". Its GOOD to find something that verifies an old "reasonableness test" prediction for once in the extrasolar zoo.

Well here's that painting I promised:

'The Diastral Sky' Nigel Gunn 1978, watercolour 70cm. by 50 cm.
Apologies - this is a low quality photo - definitely not 'validated and calibrated'.
Click to view attachment

Oops, I tried to post an improved version of that picture but it turned out worse on closer inspection - so removed.