What is the surface temperature threshold generally considered the lower boundary for a star?

Answer

Below 2,000 Kelvin

While M-Type stars often possess temperatures below 3,700 Kelvin, the lower boundary for what is still generally considered a star can dip below 2,000 Kelvin.

What is the surface temperature threshold generally considered the lower boundary for a star?
astronomytemperaturestarsstellar evolutioncommonality