In astronomy, the Kennicutt–Schmidt law is an empirical relation between the surface gas density and star formation rate (SFR) in a given region.[1] The relation was first examined by Maarten Schmidt in a 1959 paper [2] 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 in a sample of 15 galaxies could be fit with the earlier Schmidt relations with a power law index of .[3] More recently, he examined the connection between surface gas density and SFR for a larger set of galaxies to estimate a value of .[4][5]

References

  1. The name "Schmidt law" is now commonly used for a general relation between volume gas density and star formation rate, and the Kennicutt-Schmidt law for the surface gas density and star formation rate.
  2. Schmidt, Maarten (1959). "The Rate of Star Formation". The Astrophysical Journal. 129: 243. Bibcode:1959ApJ...129..243S. doi:10.1086/146614.
  3. Kennicutt, Robert C., Jr. (1989). "Star Formation Law in Galactic Disks". The Astrophysical Journal. 344 (2): 685. Bibcode:1989ApJ...344..685K. doi:10.1086/167834.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. 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. S2CID 250812069.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. Kennicutt, Robert C., Jr., Evans, Neal II (2012). "Star Formation in the Milky Way and Nearby Gaalxies". Annual Review of Astronomy & Astrophysics. 50: 531–585. arXiv:1204.3552v2. Bibcode:2012ARA&A..50..531K. doi:10.1146/annurev-astro-081811-125610. S2CID 118667387.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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