alpha element knee
zânu-ye bonpâr-e âlfâ
The point in the plot showing → alpha element abundances ([α/Fe]) of a galaxy as a function of the → metallicity ([Fe/H]) where the α-element abundance drops. The metallicity of the turn-over in α-element abundances is linked to the → star formation rate during the early stage of star formation in a galaxy and therefore also depends on the total mass of the system. Higher star formation efficiency leads to higher overall metallicity before the onset of → Type Ia supernova → enrichment, and thus to a knee that is located at higher [Fe/H] values.
1) The joint of the leg that allows for movement between the femur and tibia and is
protected by the patella; the central area of the leg between the thigh and the lower leg.
M.E. kne; O.E. cneo, cneow "knee" (cognates: O.Norse kne, O.Sax. kneo, M.Du. cnie, Dutch knie, O.H.G. kniu, Ger. Knie; cf. Pers. zânu, as below.
Zânu "knee," Mid.Pers. šnûg "knee;" Av. žnu- "knee;" cognates: Skt. jānu-, Hittite genu "knee;" Gk. gonu "knee," gonia "corner, angle;" L. genu "knee;" O.E. cneo, as above; PIE *gnéwo-.