The mass of the gaseous reservoir in young circumstellar disks is a crucial initial condition for the formation of planetary systems , but estimates vary by orders of magnitude .
In some disks with resolvable cavities , sharp inner disk warps cast two-sided shadows on the outer rings ; can the cooling of the gas as it crosses the shadows bring constraints on its mass ?
The finite cooling timescale should result in dust temperature decrements shifted ahead of the optical/IR shadows in the direction of rotation .
However , some systems show temperature drops , while others do not .
The depth of the drops and the amplitude of the shift depend on the outer disk surface density \Sigma through the extent of cooling during the shadow crossing time , and also on the efficiency of radiative diffusion .
These phenomena may bear observational counterparts , which we describe with a simple one-dimensional model .
An application to the HD 142527 disk suggests an asymmetry in its shadows , and predicts a \gtrsim 10 deg shift for a massive gaseous disk , with peak \Sigma > 8.3 g cm ^ { -2 } .
Another application to the DoAr 44 disk limits the peak surface density to \Sigma < 13 g cm ^ { -2 } .