Can someone help with this astronomy question?

Question

What is the (apparent) absolute magnitude of a stage-5 protostar? How do you caculate absolute magnitude?

Answer 1

You asked two things at once [(apparent) absolute]. Apparent magnitude is what we gauge with our eyes compared to other stars. Absolute is what we calculate with a standard distance.

My numbers may be off, but the idea is correct - Example; the sun as we see it has an apparent magnitude of -25. It's absolute magnitude is very much less, +4. What we do is calculate what the magnitude of the sun would be if we looked at it from the standard distance. I forget what that distance is, but nevertheless, this is how it's done. To your specific question of stage-5 protostar, I'm not sure, but they are so large and the total light given is not that much compared to a mature star.