When measurements are available in the distance catalogue, mup is computed as the weighted average of those measurements. Otherwise, it is determined either using the Tully-Fisher or Faber-Jackson relation for respectively spiral or elliptical galaxies.
The Tully-Fisher relation uses the corrected total magnitude
btc
and the maximum velocity of rotation vmaxg.
mup = btc + 6.5 log(vmaxg) + 6.3
The Faber-Jackson relation uses the corrected total magnitude
btc
and the central velocity dispersion vdis.
mup = btc + 6.2 vdis + 5.9
Another parameter, mucin (distance modulus), estimates the luminosity-distance using the redshift.
| HyperLeda | Questions: leda@univ-lyon1.fr |