Published online by Cambridge University Press: 14 August 2015
The details of the processes which result in the formation of new stars are still virtually entirely obscure. Surprisingly little can be said with any assurance beyond the general view that the interstellar medium collects in large clouds, involving at least tens of solar masses, which then fragment into smaller pieces which proceed to collapse into individual stars. Numerous highly detailed theoretical predictions have been generated for the sequence of events expected in the fragmentation and collapse processes. However, the meager observational evidence we have on suspected young objects is fascinatingly at variance with these predictions.