The protostar is in the middle, shown in white and green. It's not circular like the stars. You are seeing the reflection nebula of the protostar. Note the lack of stars to the left. That is due to the dark cloud blocking out the view to background stars. The Taurus cloud is very close-by, only 140 parsecs, or about 420 light years away. Most stars are much further away, so the dark cloud will block them out.