In my world, there are a number of species that stemmed from the 'original base' (humans) who traveled through space for years before a collapse in organized government crippled logistics and left colonized planets abandoned and to their own devices. After an extinction level event on the original 'base' homeworld, the other humans were left for millions of years as their technology failed and they reverted back to a stone age. By this point, some of the evolved humans are only now reaching interstellar travel once again and happening upon each other.
One such species, dubbed 'valkyries', are evolved humans possessing feathered wings protruding from just beneath the shoulder blades have adapted to live on a severely mountainous planet using these wings to keep them plummeting, though they cannot fly, only glide.
Another problem is that these valkyries are described as having a halo that hangs above their head that appears to be freestanding. How is it possible for this to be the case? be it artificial, biological, or any other means. I would like to know if it is possible for an 'angel', for sake of simplicity, to exist with a halo appearing to be freestanding above their head.