The Substellar Transition Zone: A Stretched Temperature Canyon In Brown Dwarf Population Due To Unsteady Hydrogen Fusion

I introduce an L subdwarf classification scheme, which classified L subdwarfs into three metal subclasses. I would also like to draw your attention to transitional brown dwarfs which have unsteady hydrogen fusion in their cores to replenish the dissipation of their initial thermal energy. The temperature distribution of transitional brown dwarfs are stretched to a wide range and formed a substellar transition zone. The transition zone is most significant in the old halo population and range from 1000 K to 2200-3000 K depending on metallicity. The transition zone have impacts on our observational properties of field brown dwarf population. Because field L dwarfs are composed of very low-mass stars, transition brown dwarfs, and relative younger electric-degenerate brown dwarfs.