An Etymological Dictionary of Astronomy and Astrophysics

The contraction of a volume of gas under its → gravity, accompanied by the → radiation of the lost
→ potential energy as → heat.

See also: After the Scottish physicist William Thomson, also known as Lord Kelvin (1824-1907) and the German physicist and physician Hermann Ludwig Ferdinand von Helmholtz (1821-1894), who made important contributions to the thermodynamics of gaseous systems; → contraction.