Chemical clocks in star-forming regions
The kinematics and evolutionary stages of star-forming regions can be unveiled once the right tracers of the different layers and components of molecular clouds are identified. For this, theoretical and experimental astrochemistry is needed.
In the past twenty years, observations of molecular species toward large samples of low- and high-mass star-forming regions have given us the opportunity to identify important tracers of dense gas and study their relative variations with the help of chemical models. Now, this information can be used to interpret and guide current and future large-scale molecular line observations of our Milky Way galaxy, particularly important in the Herschel era.
In this talk I will briefly describe basic chemical processes crucial for the formation of those simple species which are potential tracers of the kinematics, physical conditions and evolutionary stage of molecular clouds at galactic scales. Observational examples will be shown. I will also mention how more complex molecules can be used to study the small-scale structure and chemical evolution in the immediate vicinity of protostars, pointing out the main uncertainties.