Protoplanetary disks in the era of JWST and ALMA

• Applicant: Dr. Dmitry Semenov
• Subject Area: Astrophysics and Astronomy
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 550639632

One of the most fundamental scientific topics is understanding the origin of our solar system, other exoplanetary systems, and their properties. The physical conditions and chemical properties of the gas, ices, and solids in the protoplanetary disks where these planetary systems are formed shape their characteristics. To further progress in understanding these planet-forming disks, one must combine state-of-the-art disk physical-chemical models with realistic descriptions of physics, chemistry, dust evolution, transport, and high-quality molecular line and dust continuum observations. Powerful facilities such as the Atacama Large Millimeter/submillimeter Array and the James Webb Space Telescope produce large amounts of high-resolution and sensitivity data. At the same time, contemporary disk models must catch up in their feasibility and predictive power. This combined theoretical and observational project aims to address some of the major open questions regarding physics, chemistry, and conditions for planet formation in protoplanetary disks: • How are the C, H, O, N,- and S elements partitioned into gaseous molecules and ices in planet-forming disks? • How do gas and dust substructures affect disk chemistry? • How do gas dynamics, dust evolution, and pebble transport link the inner and outer disk regions? How strongly can these processes affect the chemical and volatile content of the planet-forming zones? In particular, I aim to investigate the distribution and evolution of the key C-, O-, N-, and S-bearing volatiles and the efficiency of isotopic fractionation and ionization in various disks around young stars on the verge of planet formation. I will use the high-quality infrared JWST and spectral line data from ALMA and NOEMA and confront it with advanced disk physical-chemical modeling. I will develop a new disk model with gas-ice chemistry, D-, C-, and O-fractionation, dust evolution, and transport. I will use this model to study disk ionization, the abundance of CHNOS volatiles, the dependence of disk composition on disk and star parameters, the impact of substructures on disk chemistry, and the link between the inner planet-forming and outer chemically pristine disk regions.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Cornelis Petrus Dullemond