There are five confirmed dwarf planets in the solar system: Ceres, Haumea, Eris, Makemake and the ex-planet Pluto. All of these planetary pretenders, apart from Ceres, are located in or around the Kuiper Belt, a disk of comets and other small objects beyond the orbit of Neptune.
Pluto is so far from the sun and still has never seen such shade.
Wait, Sedna is also a dwarf planet, isn’t it? And Gonggong? And all those other dwarf planets?
Bah gawd what have they done to my boy
Isn't that too far for habitable zone?
That's the zone for liquid water at the planet surface. There's other sources of heat; gravitational pressure, geothermal vents from plate tectonics, etc. In this case they're looking for methane with a chemical signature that indicates it comes from geothermal activity as opposed to other processes that generate methane.
I see. Thanks for the explanation.
Why methane specifically?
So that's also studies by astrobiologists looking at atmospheric methane because we know it can be created in large quantities by metabolism in an organism in addition to non organic processes, and in the atmosphere it reacts to sunlight so it needs to be replaced to stay present in large quantities.
This is something different where they're looking for chemical signatures, primarily methane, indicating geothermal vents which we've seen providing the energy to sustain life on earth at the bottom of the ocean. If abiogenesis requires some non organic processes like sublimation, evaporation, heating up and cooling down, etc to allow a self repeating process to start and continue to hold form until it's able to use sugars to continue to maintain itself instead of depending on its environment to kick start the life process then you'll want to look for those phase changes or boundaries like water/atmosphere or extreme heat/cold to provide the gradient that natural process may need like those studied in systems chemistry.