The initial mass function 50 years later

Marking half a century since Ed Salpeter's initial mass function was first published, this volume collects work from a meeting held to honour the anniversary and Salpeter's eightieth birthday. The occasion was first proposed at the IAU General Assembly in Sydney. The founding idea traces back to a short 1955 note in the Astrophysical Journal, volume 121, page 161, written in Canberra while Salpeter was visiting the Australian National University on leave from Cornell. Titled "The Luminosity Function and Stellar Evolution", it gave the first derivation of the empirical stellar mass function and introduced the terms "original mass function" and "original luminosity function". It estimated the probability that stars of a given mass form at a given time, a result now called the Salpeter Initial Mass Function.

The meeting gathered researchers who measure this quantity observationally across many kinds of astrophysical environments. It also brought together scientists who study what the function implies for theories of star formation, for the physical state of gas before and after stars form, and for the evolution of galaxies and cosmology. The gathering was held in the Tuscan countryside, a quiet setting away from everyday routine.