Neutron star

A neutron star is a stellar remnant. It is known that they have planets; however, their deadly radiation precludes a Habitable Zone. Thus, terraforming an orbiting planet is unlikely.

The star
A neutron star is a very small body (a diameter of 10 to 15 km), but with a mass of 1.4 to 5 times our sun, Sol. Matter is so tightly packed inside, that electrons merge into protons, creating neutrons. The stellar core is made of neutrons, packed together. The entire star has a density similar to an atom nucleus. Therefore, some might consider a neutron star as a giant atom.

Neutron stars are very hot. Their temperature varies from 100 000 K to millions of degrees. As so, they appear to be perfectly white to the naked eye, even if the largest part of their light is in ultraviolet and X - rays. Their overall energy output is not high. If one neutron star is to be placed instead of Sol, Earth will face temperatures similar to Uranus, but the deadly radiations will kill any living creature as far as Ceres. The star does not emit the same amount of light in each direction. So, since it spins fast, it appears to change its light intensity very fast.

Neutron stars have a gigantic gravity force. Their escape velocity is 100 000 km/s. So, only light can leave them. If an object (for example a grain of dust) falls on such a star, gravity acceleration will increase its speed and it will fall with so much energy, that it will generate an explosion of X and gamma rays. Neutron stars seem to accumulate more heat from accretion of matter than they can radiate on their small surface. However, compared to the lifetime of a settler, there is nothing to worry.