On the robustness of the H$\beta$ Lick index as a cosmic clock in passive early-type galaxies

A. Concas, L. Pozzetti, M. Moresco +1

We examine the H$\beta$ Lick index in a sample of $\sim 24000$ massive ($\log (M/{\mathrm{M}}_{\odot })>10.75$) and passive early-type galaxies extracted from SDSS at z<0.3, in order to assess t…