In astronomy, the Kennicutt-Schmidt law (or simply Schmidt law) is an empirical relation between the gas density and star formation rate (SFR) in a given region. The relation was first examined by Maarten Schmidt in a 1959 paper where he proposed that the SFR surface density scales as some positive power of the local gas surface density. i.e.
In general, the SFR surface density is in units of solar masses per year per square parsec and the gas surface density in grams per square parsec . Using an analysis of gaseous helium and young stars in the solar neighborhood, the local density of white dwarfs and their luminosity function, and the local helium density, Schmidt suggested a value of (and very likely between 1 and 3). All of the data used were gathered from the Milky Way, and specifically the solar-neighborhood.
In 1989, Robert Kennicutt found that the H intensities of every galaxy in a sample of 7 could be fit with the Schmidt law. More recently, he examined the connection between gas density and SFR for nearly 100 nearby galaxies to estimate a value of .
- Schmidt, Maarten (1959). "The Rate of Star Formation". The Astrophysical Journal. 129: 243. Bibcode:1959ApJ...129..243S. doi:10.1086/146614.
- Binney, James; Merrifield, Michael (1998). Galactic Astronomy (1st ed.). Princeton, NJ: Princeton University Press. p. 524. ISBN 978-0-691-02565-0.
- Kennicutt, Robert C., Jr. (1998). "The Global Schmidt Law in Star-forming Galaxies". The Astrophysical Journal. 498 (2): 541–552. arXiv:astro-ph/9712213. Bibcode:1998ApJ...498..541K. doi:10.1086/305588.CS1 maint: multiple names: authors list (link)