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 in which he proposed that the SFR surface density scales as some positive power n of the local gas surface density. i.e.
Σ S F R ∝ ( Σ g a s ) n .
In general the SFR surface density ( Σ S F R ) is in units of solar masses per year per square parsec ( M ⊙ yr − 1 pc − 2 ) and the gas surface density in grams per square parsec ( g pc − 2 ) . 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 n ≈ 2 (and very likely between 1 and 3). All of the data used were gathered from the Milky Way, and specifically the solar-neighborhood.
More recently, Robert Kennicutt examined the connection between gas density and SFR for nearly 100 nearby galaxies to estimate a value of n = 1.4 ± 0.15 .
