B - type star

B - type stars (blue-white) are very rare, but because of their extreme luminosity, they form the majority of stars visible on the sky. Because they are located at high distance, their systems cannot be colonized until interstellar transport will pass the speed of light. Such a star might host a gigantic Habitable Zone.

The star
Almost all important stars are in fact B - class stars. Some of the most known are the 7 Pleiades, Rigel and Deneb.

Luminosity of such a star is very powerful. For two stars, Rigel and Deneb, luminosity is shown below:

Bolometric luminosity (entire spectra, including non-visible light): It is easy to see from this scheme that these stars emit less light in visible spectra. So where is the extra light? According to blackbody radiation theory, for such a hot body (over 20 000 K), the majority of radiation will be generated in ultraviolet. More even, the star will generate less red light and a lot more blue light.
 * Sol - 1
 * Rigel - 120 000
 * Deneb - 200 000
 * Visual luminosity (only visible light):
 * Sol - 1 (100%)
 * Rigel - 38 600 (31%)
 * Deneb - 67 000 (33%)

The environment surrounding Rigel or Deneb is full of magnetic fields and solar winds. This is because such stars spin very fast. Pleione, one of the Pleiades, is spinning so fast, that it has a visible ellipsoidal shape. Even more, it is losing matter from its equator, creating a glowing disk around. Such fast rotating stars create huge magnetic fields around. On the other hand, these stars end their hydrogen very fast. Deneb stopped fusing hydrogen and is in a small break, waiting to start using helium. When this happens, massive convection currents mix all matter inside the star, pushing any available hydrogen into the nucleus. When these currents appear, magnetic fields also suffer.

Fast spinning stars lose matter from their equator, to be blown away by radiation pressure, feeding the solar wind. These stars have more diffuse atmospheres, so that under their huge radiation pressures matter is more easily thrown into solar wind. Because of this, some astronomers assume that B - class planets cannot have planets, until some were discovered. Planets could have formed from a planetary disk or they can be captured.