A Tentative Size-Luminosity Relation for the Iron Emission-Line Region
  in Quasars
  New reverberation mapping measurements of the size of the optical iron
emission-line region in quasars are provided, and a tentative size-luminosity
relation for this component is reported. Combined with lag measurements in
low-luminosity sources, the results imply an emission-region size that is
comparable to and at most twice that of the H$\beta$ line, and is characterized
by a similar luminosity dependence. This suggests that the physics underlying
the formation of the optical iron blends in quasars may be similar to that of
other broad emission lines.
