Cartoon of Disk Evolution
A young, accreting disk, made of well-mixed dust and gas.
Some grain coagulation and sedimentation are happening...
Transition object: the inner disk is optically thin, but there is still some accretion...
... until the accretion ceases. And maybe you have some planets!
How to make nice disks pictures? I did it in almost no time with
the program "oodraw", which is part of OpenOffice, plus some gimp to add accretion funnels and
other details.