Simple enough question. I know there are two types of black holes; the type formed after a star collapses in a supernova and the supermassive variety like the one at the center of the milky way. If a star continued to grow by swallowing up other stars and solar systems is it possible that at a certain point its gravitational field would become so strong that light and heat could no longer escape? It would be a tipping point. Prior to reaching that mass it would be a bright star, but as it continued to grow it would start to dim as some wavelengths of the electromagnetic spectrum could no longer escape the massive star's gravitational field. Eventually it would reach such a size that it would appear dark to an observer, but in reality it is a bright and hot star that can no longer be conventionally detected.