Astrophysics & Particle Physics-APPC 2026

Atomic and Molecular Astrophysics is the study of the behavior, structure, and interactions of atoms and molecules in the cosmos. It is a merger of atomic physics, molecular physics, quantum mechanics with astrophysical observations to know the chemical composition, dynamics, and evolution of the universe.Spectroscopic methods are at the core of the subject, and using these, scientists are able to investigate atomic and molecular transitions from stars, planetary nebulae, and the interstellar medium.

Emission and absorption lines indicate temperature, density, chemical composition, and physical conditions of astronomical objects. Molecular astrophysics treats interstellar molecules, molecular clouds, and star-forming regions. Hydrogen (H₂), carbon monoxide (CO), and complex organic molecules are important for cooling processes, chemical evolution, and the formation of stars and planetary systems. Studying these molecules tells us about astrochemical processes and the origins of life.Atomic astrophysics also examines stellar atmospheres, atomic transitions, ionization states, and radiative processes, which are required to comprehend stellar evolution, nucleosynthesis, and energy transport in the stars. With the integration of atomic and molecular information and observation through radio, infrared, and optical telescopes, fine-scale modeling of cosmic environments is made possible.The discipline also overlaps with astrochemistry, which examines chemical processes in space, the creation of complex molecules, and the interaction between radiation and matter.

Understanding atomic and molecular processes is essential for interpreting high-resolution spectra, planetary atmospheres, and the dynamics of interstellar clouds.By studying atomic and molecular astrophysics, scientists gain insight into the physical and chemical processes shaping the universe, from the smallest scales of molecules to the largest star-forming regions. This field offers a linkage between quantum physics and observation astronomy so that scientists can investigate the structure, development, and motion of cosmic environments in ways never before possible.