A - type star

A - type stars are more rare than K - type stars, G - type stars or F - type stars (which are similar to our sun, Sol). Because of their luminosity, they are the second most common stars in the night sky, after B - type stars. Some of the brightest stars we see are A - type stars, including Sirius A, Vega, Altair or Fomalhaut. As long as speed of light remains a hard barrier for cosmic transportation, many settlers will look at these stars as possible destinations. They have a large Habitable Zone.

The star
A - class stars have strong solar winds, much stronger then Sol. Their lifetime is far shorter. Once they have used all hydrogen, they begin to fuse helium, slowly leaving main sequence and transforming into red giants. In the end, they become white dwarfs. This is not a problem for settlers, because human lifetime is extremely small compared to a star.

These stars do have planets. In fact, one of the first extrasolar planet was discovered around Fomalhaut. Some people suggest that since these stars have a shorter lifetime, planets would not have enough time to develop into Earth-like bodies (if continents exist, they would be small and highly volcanic). However, a well-established planet could have been captured from another star.

A - class stars are more massive then Sol and they spin faster, creating a more powerful magnetic field. Despite this, solar flares are not a threat to nearby planets, compared to the average solar wind. There is also an advantage: the strong magnetic field, completed with a powerful solar wind, keeps interstellar environment further away from the planet.

Based on the blackbody radiation theory, the peak of Sirius's radiation is somewhere between blue and ultraviolet, while for Sol, it is in yellow. As a direct result, A - class stars generate a lot of UV radiation. In visible light, they produce more blue then red light and far less infrared light.