When Didier Queloz did the work that earned him a Nobel prize (along with Michel Mayor), he was still a PhD student.
Jocelyn Bell Burnell stated
I believe it would demean Nobel Prizes if they were awarded to research students, except in very exceptional cases
What made this case so exceptional that he got the Nobel in spite of having been a PhD student at the time? Why wasn't the Nobel just awarded to his supervisor, Michel Mayor?