Its namesake "modulus" relates the difference between the absolute and apparent magnitudes to this quantity.
One method for determining this is named for Faber and Jackson and suggests that luminosity is roughly proportional to sigma to the fourth. An analogous operation on spiral galaxies calculates it by determining the velocity width, called the Tully-Fisher relation. Alternatively, it may be found by looking at nearby type Ia supernovae or at the object's recession velocity. Its namesake "modulus" relates the difference between the absolute and apparent magnitudes to this quantity. FTP, identify this quantity that can be measured in astronomical units.
One method for determining this is named for Faber and Jackson and suggests that luminosity is roughly proportional to sigma to the fourth.
{distance} (accept {modifiers} like {interstellar}, etc.)