At the center, the main star forms. Out further, smaller eddies can form planets. Until recently, we did not have any evidence of planets outside our solar system. This exciting discovery increases the likelihood of other planets around many stars. Geoffrey Marcy is a professor at San Francisco State University.
Small stars are cool and red.
Planets would have to orbit very close to be in the ecosphere. Not much room for planets. Planets that orbit very close to their parent star are often tidally locked and present one face to the star at all times. On the other hand, huge hot blue stars have a farther and wider ecosphere. Of course, judging from our solar system, planets are spaced further apart the farther they are from the star, so the wider ecosphere is cancelled by this effect.