Birth-age distribution under constant star formation
= Birth-age distribution under constant star formation
{title2=$Y(t)=t/T\quad(0\le t\le T)$}
If a population forms at a constant number rate for duration $T$ and every birth object is retained in the census, its present ages are uniform on $[0,T]$. A fixed <initial mass function> with finite mean birth mass also makes constant mass-based <star formation rate> equivalent to constant number rate.