Q2 What does the phrase 'containing several distinct knots of collopsing material' mean?
Q3 In this context, does the word 'such clouds' mean protostar? (I'm not an English-native speaker.)
Q4 In the context, does the word 'a spinning disc' mean an Accretion disk ?
Q1 And the last... Could you explain 'spiral density wave' to me if you can?