Red Dwarf star, much closer than 4.5 light years..........
We see brown dwarfs with infrared telescopes. The same with red dwarfs. Red dwarfs make up something like 80% of the stars in the universe.
Red dwarfs do emit visible light but they’re pretty dim so not one is visible with the naked eye from earth. The nearest is Proxima Centauri at 4.5 light years.
According to Wikipedia, Proxima Centauri is 400 times as far from Alpha Centauri A & B as Neptune is from the sun, and would appear only as a fifth-magnitude star viewed from Alpha Centauri. Apparently it hasn’t been conclusively proven that it is gravitationally connected with the two brighter stars although it seems to be.
Red Dwarf star, much closer than 4.5 light years..........