Aero-Terms!

Aero-Terms are designed to be a daily reminder of the terms, names, acronyms and explanations of the unique language that populates the aviation world. Aerospace, sport aviation, fixed wing, helo, you name it... it's all fair game.

Aero-Terms should serve as a quick but intriguing reminder of the terms you may use every day, or an introduction to an aspects of the Aero-World you may not yet be familiar with. ANN also encourages readers to go beyond the FMI link, and further research any intriguing terms.

Suggestions for future Aero-Terms are ALWAYS welcome, as are additions or discussion of the explanations given for each Aero-Term.

Faber-Jackson Relation 

An observed correlation between the random speeds of stars in the center of an elliptical galaxy and the intrinsic luminosity of the galaxy - the higher the random speeds, the more luminous the galaxy. Since the speeds of stars can be directly measured by the Doppler shift in their spectra, the Faber-Jackson relation gives a way of estimating an elliptical galaxy's intrinsic luminosity. By comparing this with the observed brightness, the distance to the galaxy may be inferred. It is named after the American astronomers Sandra Moore Faber (1944-) and Robert Earl Jackson (1949-). See also the Tully-Fisher relation, which is applied to spiral galaxies. 

FMI: http://en.wikipedia.org/wiki/Faber-Jackson_relation