Astrophysics (index)

Tully-Fisher Relation

(relation between spiral galaxy luminosity and line width)

The Tully-Fisher Relation (TFR) is a relation between the Luminosity of a Spiral Galaxy and the width of its Emission Lines. The luminosity is related to the Galaxy's stellar mass and the Emission Spectral Line width is a measure of its rotation velocity. Thus Doppler Shift measurements of the rotation yield an estimate of its luminosity, making it a Standard Candle, whose distance can be estimated.

The Baryonic Tully-Fisher Relation (BTFR) is a variant, specifically using K Band measurements, which more closely relate to the stellar mass. The baryonic mass is related to the velocity to the power of 3.5 to 4.


Referenced by:
Cosmic Distance Ladder
Faber-Jackson Relation
Standard Candle