Outer disks of lenticular galaxies
  By studying the stellar population properties along the radius in 15 nearby S0 galaxies, I have found that the outer stellar disks are mostly old, with the SSP-equivalent ages of 8-15 Gyr, being often older than the bulges. This fact puts into doubt a currently accepted paradigm that S0 galaxies have formed at z=0.4 by quenching star formation in spiral galaxies. 
Olga K. Sil'chenko (Sternberg Astronomical Institute of the Lomonosov   Moscow State University)
astro-ph.CO