Numerical Model runs describing the D/H ratio of the sublimating gas as a function of time and dustiness for the H
O-HDO system and starting concentrations relevant to the experiments documented in Figure 5. Substitution is assumed negligible. The value of α
is set at α
/0.6. The dustier the original starting material the faster each curve approaches the limiting value of D/H = α
= 0.6 (D/H)0. Different values for α
will produce different timescales for reaching the asymptotic D/H ratio. A reasonable value, 7000, is shown here.