There is a lot of new data from the various extrasolar planet projects including NASA's Kepler mission on extra-solar planets. Based on our current data what is the probability that a star of each of the main spectral types (O, B, A, etc) will have a planetary system?
[Physics] the probability that a star of a given spectral type will have planets
astronomyexoplanetsspectroscopystars
Best Answer
Almost all exoplanets observed are near F, G, and K stars. In part, this is because astronomers are looking for earth-like planets, so they look at stars similar to our Sun, but there are also some physical reasons. Sahu et al (2006) have provided some evidence that red dwarfs (class M) are more likely to have planets than other spectral types, though it is hardly conclusive; in any case, planets have been observed around red dwarfs.
No exoplanets have been observed around very massive UV stars (O and B spectral types), and only a few around still-large A-stars. This is probably because very massive stars blast away the protoplanetary disk before accretion allows formation of planets. This was covered in a recent paper by Gorti and Hollenbach (2009).
Incidentally, the most important predictor of whether a given star will have planets is its metallicity. This has been known for quite a while, but Geoff Marcy and company found this most dramatically in a 2005 survey - they estimate that 25% of high-metallicity stars have planets, while only 3% of low-metallicity stars have planets. It's not totally understood why planetary formation depends so strongly on metallicity, but many reasons have been proposed: metallic stars have lower stellar winds, less total UV flux, and their protoplanetary disks are probably more enriched with silicon and iron, which speeds up planet formation.