The formation of exoplanetary systems is contingent on the availability of raw material in the parent disk environment. The type of planet formed (rocky or gaseous) at a particular location is…

This is a grant for research awarded by the National Aeronautics and Space Administration (NASA) to the SETI Institute, a non-profit scientific research organization. The research project aims to use new chemical models to estimate the mass of gas in protoplanetary disks and compare this to the inferred mass of dust, in order to understand the evolution of the mass reservoir during planet formation. This research is directly relevant to improving the understanding of the origins of exoplanetary systems and the composition of exoplanets, aligning with the objectives of NASA's Exoplanets Research Program. The grant has a ceiling value of $466,314.00 and a completion date of December 31, 2024. No set-aside designation was used for this award.

The formation of exoplanetary systems is contingent on the availability of raw material in the parent disk environment. The type of planet formed (rocky or gaseous) at a particular location is expected to depend on the relative masses of gas and dust in the disk. Moreover, current theories argue for a decrease in the gas/solids ratio to enable the first critical stages of planetesimal formation. Dust emission is now known to decline with system age. Recent surveys for star-forming regions further indicate that the dust in disks undergoes evolution in accordance with what is expected theoretically. However, tracking the gas mass has been far more difficult with the hitherto reliable CO component being frozen on grains and perhaps subject to chemical effects. We propose to use new, upto- date disk chemical models that include isotope selective photo-dissociation and grain chemistry to estimate the mass of gas in disks. We will also RE-visit continuum-based estimates of dust mass from extant surveys. From independent assessments of the two, we will compare the inferred gas/solids mass ratio in disks with disk evolution and planet formation theories. We will thus evaluate how the mass reservoir in proto-planetary disks evolves during planet formation epochs. The proposed research is directly relevant to improving our understanding of the origins of exoplanetary systems and of the composition of exoplanets (predominantly rocky, ICY or gaseous), and hence aligned with the objectives of the NASA exoplanets research program.