Astrophysics & Particle Physics-APPC 2026

Protoplanetary Disks are spinning gas and dust disks around young stars, the nurseries of planets and planetary systems. They form naturally during star formation, as material from a collapsing molecular cloud conserves angular momentum and flattens into a disk around the central protostar.The structure of protoplanetary disks typically consists of a dense inner region close to the star, a cooler outer disk, and often a disk atmosphere with less dense material. The gas and dust in the disk experience processes like fragmentation, accretion, and coagulation, which result in the creation of protoplanets, planetesimals, and finally planets.Disk evolution is affected by magnetic fields, stellar radiation, turbulence, and planet-forming interactions.Disks can disperse within a span of a few million years through accretion onto the star, planet formation, or photoevaporation, which defines the phase transition to mature planetary systems.

T Tauri star and Herbig Ae/Be star observations give a critical perspective on disk and evolutional status.We observe protoplanetary disks with multi-wavelength astronomy, especially infrared and millimeter observations by ALMA (Atacama Large Millimeter/submillimeter Array) telescopes. These observations uncover disk morphology, dust rings, gaps, chemical composition, and kinematics, illuminating the process of planet formation.Chemical processes within the disk, such as complex organic molecule production, are essential to understanding the possibility of habitable environments in nascent planetary systems. Through the observation of protoplanetary disks, astronomers learn about the formation of planets, planetary structures, and the physical processes that control star and planet formation.Protoplanetary Disks form the cornerstone of contemporary astrophysics, linking star formation to planetary system evolution, and acting as natural laboratories for examining disk dynamics, astrochemistry, and mechanisms of planet formation throughout the universe.