Other contributors have said "What affects brightness of stars?" is the same question as "What affects the brightness of stars?" If you believe that these are not asking the same thing and should be answered differently, click here
Yes as if it isn't hot enough to fuse rapidly the hydrogen atoms then it will not create enough photons to be bright in the sky and we wouldn't be able to see it easily.
Here the two things that we must take into account are , the distance of the star from the earth, and secondly the great distance of the star from the earth.