Chemistry and Organic Molecules in Protoplanetary Disks

Hideko Nomura (NAOJ)


Protoplanetary disks are the natal place of planets and understanding chemical compositions of gas, dust and ice in the disks will help us to understand the origins of materials in our Solar system. Now, ALMA (Atacama Large Millimeter/submillimeter Array) enables us to detect complex organic molecules (COMs) in the disks, CH3CN and CH3OH, which would lead to more complex organic compounds, such as those found in the comet 67P/Churyumov-Gerasimenko by the Rosetta mission. Protoplanetary disks are known as the object of chemical diversity because the physical structure dramatically changes depending on the distance from the central star which is the main source of heating and UV radiation. We investigate the synthesis of COMs in the disks using a large gas-grain chemical network together with a 2D steady-state physical model of a disk irradiated by UV and X-rays from the central star. Radical-radical reactions on warm grain surface as well as hydrogenation reactions on cold grain surface are considered in the reaction network. In addition, we are extending our work, taking into account possible carbon grain destruction and including grain mantle reactions which could proceed in the region where water ice is crystallized in the disks. I will also talk about some related astrochemical phenomena in the disks.

host contact: Misako Tatsuuma