I did a search, and i can't find anything similar to this.
I made a brown dwarf star a few versions of space engine ago. 0.971 i think. I'm not sure. I made a planet around that brown dwarf in the habitable zone for liquid water ( it was very close, like ~0.002 AU or something), but when i updated Space Engine some time after the brown dwarf stars were much hotter and i had to move my planet much farther from the brown dwarf to have water on its surface. (had to move it to about ~0.02 AU)
I just want to know, are the brown dwarfs accurate in the old version of space engine or the new one? What should i trust? I try to use this calculator http://depts.washington.edu/naivpl/sites/default/files/index.shtml to find the habitable zone and it shows it is much closer then what the new space engine says so i dont know. but maybe brown dwarfs work different?
One last little question. does the class of brown dwarf change with age? If so how old of a brown dwarf would you say is ok to use to have a planet with water for a billion years or so before it freezes. its hard to find things on the topic.
I think brown dwarfs are still bugged in space engine as an M9 dwarf holds terras in 5-10 day orbits while the cooler and smaller brown dwarfs are holding them around 20+ day orbits which doesnt make sense. Brown dwarf should hold them closer to what you are calculating.
Second part: As of right now brown dwarf class is only determined by its mass. The higher the mass the hotter it's generated. Their temperature will probably be affected by their age at a later date.
Lastly, its possible but only with the highest massed brown dwarfs as the lower massed ones will radiate most of their heat after a few million years. Note: If the planet is mildly eccentric, it can stay warm almost indefinitely through tidal heating alone.