NASA found remnants of the planetary system in the Helix Nebula. That thing is one of the most interesting things that ever found. Helix Nebula is the supernova remnant. And that means the star was too heavy and short-living, that there could form technically advanced civilization. But those planetary remnants tell that there is a possibility that also around white dwarfs can be remnants of planetary systems. The white dwarf is the star remnant. That is interesting because our Sun will transform into a white dwarf after a couple of millions of years. And if we want to find alien civilizations that can make interstellar journeys, we should look for evidence around star remnants that are out of their fuel. In that case, the civilization must move to another solar system or its fate will be destroyed when its star will erupt as a nova or supernova. "The spectral energy distribution of WD 2226-210 superposed on an image of the Helix Nebula from Hubble Space Telescop...
For finding solutions for problems, we must not claim that some proposition is right or wrong. All possibilities are open. Until they are proven right or wrong using empiric methods that are scientifically accepted.