Paul Ledoux

Paul Ledoux (8 August 1914 – 6 October 1988[2]) was a Belgian astrophysicist best known for his work on stellar stability and variability. With Theodore Walraven, he co-authored a seminal work on stellar oscillations.[3] In 1964 Ledoux was awarded the Francqui Prize for Exact Sciences, and was awarded the Eddington Medal of the Royal Astronomical Society in 1972[4] for investigations into problems of stellar stability and variable stars. He was awarded the Janssen Medal of the French Academy of Sciences in 1976.

Paul Ledoux
Paul Ledoux
Born(1914-08-08)8 August 1914
Forrières, Belgium
Died6 October 1988(1988-10-06) (aged 74)
Liège, Belgium
CitizenshipBelgian
Alma materUniversity of Liège
Known for
  • Ledoux criterion
Awards
Scientific career
FieldsAstrophysics
InstitutionsUniversity of Liège

Ledoux criterion

In stellar astrophysics, Ledoux's name is now associated with the criterion under which material in a star becomes unstable to convection in the presence of a gradient of chemical composition. In homogeneous material, the Schwarzschild criterion shows that material is unstable to convection if the radiation field alone would establish a steeper temperature gradient steeper than the adiabatic (or isentropic) temperature gradient. However, Ledoux showed that a composition gradient stabilises or destabilises the material against convection.[5] In convectively-stable regions destabilised by the composition gradient, one expects thermohaline mixing; in convectively-unstable regions that are stabilised, one expects double-diffusive mixing, known in stellar astrophysics as semiconvection.

References
  1. "Fondation Francqui - les Colloques Internationaux". Archived from the original on 2016-03-05. Retrieved 2016-09-29.
  2. Swings, J. P. (1989), "Obituary - Ledoux Paul", Astrophysics and Space Science, 155: 179, Bibcode:1989Ap&SS.155..179S
  3. Ledoux, P.; Walraven, Th. (1958). "Variable Stars". Astrophysics II: Stellar Structure / Astrophysik II: Sternaufbau. Encyclopedia of Physics / Handbuch der Physik. Vol. 11 / 51. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 353–604. Bibcode:1958HDP....51..353L. doi:10.1007/978-3-642-45908-5_6. ISBN 978-3-642-45910-8.
  4. Hoyle, F. (1972), "P. Ledoux received the Eddington Medal.", Quarterly Journal of the Royal Astronomical Society, 13: 348, Bibcode:1972QJRAS..13..485H
  5. Ledoux, P. (1947), "Stellar Models with Convection and with Discontinuity of the Mean Molecular Weight", The Astrophysical Journal, 105: 305, Bibcode:1947ApJ...105..305L, doi:10.1086/144905


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