Far and mid-infrared studies of star forming regions: Probing their thermal balance, chemistry and evolution

The goal of this thesis is to understand the physical and chemical processes that take place in regions forming stars, in particular during the early evolutionary stages of star formation. Why do we care about stars and star forming regions? Many elements on Earth were once formed in the heart of a star. In particular the building blocks of life, known as organic molecules which contain both carbon and hydrogen, have also been found towards star forming regions. While staring at the stars, one should bear in mind, that the starlight we enjoy, shares its origin with the light that actually triggers the chemical reactions quintessential for the formation of Earth and life. In order to understand how stars form, this thesis investigates the role of various molecules in the thermal balance (heating and cooling) of star forming regions, which controls their stability. In addition I investigate the stages that a star goes through during the process of formation and the chemical composition of newly forming stars. Young stars are hidden from optical telescopes because they are deeply embedded in dense clouds of gas and dust. However, infrared radiation, can pass through allowing us to study these regions. The present thesis aims to study these places that give birth to stars of various masses using infrared instruments and to provide some answers in regard of the open questions in the field of star formation.