The good news about that study is that if we can ever get out of this system, there are multitudes of other systems that either have potential planets in a stable, habitable zone, or we can build colonies in that area if it's not occupied. Or both. As for finding actual life out there, I still believe the odds are favorable for life somewhere else in the galaxy. But we may be it. It's best to assume that we are the universe's only awareness, and struggle to protect all of Earth's life, for if we extinquish it, and it IS the only form of life, shame on us.
This 'not too hot, not too cold' zone for life does not sound feasible. Maybe 'unstable' planets support life, like the earth which vibrates more than other planets due to the single moon. The chemical nature would be to pair up unstable atoms to reduce the vibration, this would lead to long chain molecules, the basis for life. Though this means that the chemical nature of the planet is 'doped' by the nature of the planet. (there is only meager evidence for this at the moment) Uranus is another unstable planet in our solar system, maybe there is life on uranus (no pun intended). You would think that any one area of the universe would contain similar types of objects, life bearing planets may be grouped into small regions.
Earth's own orbit changes its distance from the Sun by millions of kilometres over the year. I believe Q posted a very nice graphic of supposed habitable zones a while back.
