Phd Projects at CAS

PhD Project in Theory

Regions of the interstellar medium filled with atomic and molecular gas are the environments where the first stages of star formation occur. The nested hierarchical structure of molecular gas distribution, from diffuse giant clouds of up to hundreds of pc, through denser ~10 pc clouds and pc-sized clumps, down to very dense sub-pc cores, has a complex filamentary shape. Impressive recent progress in observing molecular gas and dust at different spatial scales has greatly improved our understanding of the density distribution in such environments. Combining these observations with sophisticated models of radiative transfer and applying recent advances in the theory of cosmic ray (CR) propagation in molecular gas makes it possible to self-consistently compute detailed physical and chemical structure of molecular clouds.

CRs are the main source of ionization of molecular gas. Interaction of the ionized hydrogen with neutral hydrogen molecules quickly leads to the formation of H3+ ions. These ions, in turn, trigger a chain of chemical reactions between charged and neutral gas species, producing several other key molecules. The ongoing activity of the CAS Theory Group in studying the CR transport and applying these models to nearby diffuse molecular clouds has delivered all essential ingredients necessary to start exploring the first stages of gas-phase chemistry in these objects.

We offer a Ph.D. position with the topic of CR-driven chemistry in diffuse molecular clouds. The work will be carried out at the interface between the CR theory and astrochemistry. It will be focused on analyzing observationally constrained ionization in nearby molecular clouds, applying and developing available chemical models to compute the formation of key molecular species in these regions, and providing predictions for future dedicated observations. The Ph.D. candidate will work in close collaboration with the members of CAS-Theory group, and will obtain necessary support and complementary advice from experts in astrochemistry and observations.

Supervisor: Dr.  Alexei Ivlev

 

PhD Project in Laboratory

In preparation for the upcoming observing facilities that will observe exoplanets, such as the ELT, ARIEL, and VLTI/ GRAVITY+ and the recently launched JWST, laboratory work is necessary. These facilities will provide an unprecedented sample of spectra of exoplanetary atmospheres and will, therefore, build a 'standard model' of how a planet's chemistry depends on its star and the condition of its birth. Laboratory data on stable molecules that compose exoplanetary atmospheres, however, are far from complete, especially at high temperatures. The impact of dominant gases on the trace species is also rather unknown, thereby making the determination of molecular abundances difficult. Infrared laboratory spectra will therefore be critical to interpret the upcoming data on exoplanetary atmospheres. This PhD project will be focused on high-resolution laboratory infrared spectroscopy to determine the effect of broadening induced by temperature and pressure with a set of different broadeners, to account for the different chemical environments. Supervisor: Dr. S. Spezzano