Contribution Contributed Talk
Disk mass determination through CO isotopologues
One of the key properties for understanding how disks evolve to planetary systems is their overall mass, combined with their surface density distribution.
So far, virtually all disk mass determinations are based on observations of the millimeter continuum dust emission. To derive the total gas + dust disk mass from these data involves however several big assumptions. The alternative method is to directly derive the gas mass through the detection of carbon monoxide (CO) and its less abundant isotopologues. CO chemistry is well studied and easily implemented in chemical models, exception made for isotope-selective processes.
For the first time CO isotope-selective photodissociation was implemented in a full physical-chemical code (Miotello et al., 2014). The main result is that if isotope-selective effects are not considered for the data analysis, disk masses can be underestimated by an order of magnitude or more. For example, the mass discrepancy found for the renowned TW Hya disk may be mitigated by this implementation. We show that if CO isotope-selective photodissociation is implemented and if atomic carbon (C) is depleted by a factor of 10, the puzzle of TW Hya disk mass is solved (Miotello et al., in prep.). Moreover, mass correction factors are derived and provided for different disk properties in order to account for isotope-selective effects (Miotello et al., in prep.).