I can say that Habitable Zones are traditionally defined as the region around a star where surface water can exist; that being said, again, there are multiple facotrs involved. Our studies of the outer moons show that subsirface liquid water can exist, which, combined with our knowledge of deep sea “smoker” ecosystems means there’s a distinct possibility of basic life there. Other conditions and forms of life have also been explored (I highly recommend Peter Ward’s Life As We Do Not Know It, which allow for the possibility of life outside standard search areas (i.e. Earth-like worlds). Returning tothe standard parameters, however, as many of you pointee out, armospheric retention and loss is also something to consider, as well as magnetospheres, the presence of a sufficiently sized lunar body to protect against impacts, the presence of a jovian body to “sweep” the system clean during formation, and sufficient distance from the host star to prevent tidal locking – a feature not present in red dwarf systems, due to their zones lying entitely within tidalnlocking areas.

Again, though, these parameters are all based off our world, since it’s the only confirmed environment where life exists naturally – one way or another, future observations in this area will be enlightening.