From Molecular Clouds to Dense Cores

We have an active and diverse program to study the properties of molecular clouds and their connection with dense cores. Since molecular clouds provide the initial conditions for dense cores, it is important to determine some of their main properties: the amount of turbulence in the molecular cloud and inside dense cores, the amount of energy radiated by turbulent dissipation, and the role of magnetic fields. We have studied distant Infra-Red Dark Clouds (IRDCs) and nearby molecular clouds in dense gas tracers, using both single dish and interferometers, to reveal a large fraction of dense gas (as traced by NH3) present in the intra-core medium and to highlight the presence of subsonic turbulence inside dense cores even in the higher-mass star-forming regions traced by IRDCs. The relation between the kinematics and other physical properties of the dense cores and their parental molecular clouds has been explored. In addition, a systematic study of mid-J to high-J CO transitions in IRDCs provided a possible detection of the energy generated by turbulent dissipation. Finally, a comparison between Planck and polarization of background stars was carried out and it showed small differences between both techniques, confirming the validity of the Planck based polarization measurements in molecular clouds.

Dense Cores

Dense cores are regions within interstellar molecular clouds where stars like our Sun form. In the CAS group a lot of effort is put into studying dense cores with the aim of deriving more constraints for star and planet formation. The collaboration among observers and modellers, as well as the input from laboratory spectroscopists, are crucial to make progress and have a full understanding of the chemical and  physical evolution of dense cores. In particular, we focus our attention on the information that can be inferred from isotopic fractionation in dense cores on their physical and  chemical evolution. Furthermore, we want to understand and  exploit all the information that is carried by the chemical segregation in dense cores, not only to better constrain our chemical networks, but also to derive the physical structure of the core.

The Evolution of Circumstellar Disks

Young circumstellar disks regulate the accretion of material from protostellar envelopes to protostars and, in later stages, provide the physical conditions for planet formation. The research done in the CAS group spans several stages of disk evolution, from young embedded disks to more evolved protoplanetary disks. We use state-of-the-art instrumentation
including ALMA, NOEMA, and SOFIA which cover a range of observational frequencies and spatial resolutions. Here we present the advancements made by the CAS group using observations of molecular lines, polarization, and dust continuum data.
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