2024.04.04 - Alessio Traficante
Channel: Coloquio IRyA
Date: 2024-04-05

Speaker info: Dr. Alessio Traficante, INAF-IAPS, Rome

Title: From clouds to fragments: on the multi-scale interplay between gravity and turbulence

Abstract:
The star formation mechanism occurs in well defined structures that
 can be identified and studied in great details in our own Galaxy: the 
process starts in giant molecular clouds, objects extended up to several
 tens of parsecs, within which elongated sub-structures, called 
filaments, may form. Inside filaments, round-like condensations extended
 up to ~1pc in radius, the so-called clumps, are the natural birth site 
of the pre- and proto- stellar fragments, inside which will origin the 
future stars.There are still many open questions in this hierarchical view of the star formation process: are these structures relatively confined from each other,  or is the large-scale environment affecting the dynamics of the formation down to clumps and fragments? Is there a continuous interplay of the various forces involved in the process, namely turbulence, gravity, at all scales? Or is there a relevant scale at which gravity will start to 
dominate the collapse, with critical implications on the star-formation 
mechanism? After a general overview of the problem, I will present in details some recent results focused on the interplay between gravity and turbulence at the filament, clump and fragment scales. To investigate this 
interplay at the larger scales, we have combined the dynamics of 
so-called 70 micron quiet clumps, i.e. very pristine regions not yet 
strongly affected by feedbacks, with the dynamics of the parent 
filaments in which they are embedded. At smaller scales, I will discuss 
the different scenarios of fragments formation in light of the most 
recent results from the SQUALO (Star formation in QUiescent And Luminous Objects) project. This ALMA survey has been designed to investigate the formation properties in a sample of massive clumps selected to be at various evolutionary stages and with the common feature that they are all accreting at the clump scales. Our results show that a large scales we observe a continuous interplay between turbulence and gravity, where the former creates structures at all scales and the latter takes the lead above a critical value of the surface density is reached, ~ 0.1 g cm^-2. At the same time, the fragmentation properties show several indications that the fragment are ""clump-fed"", i.e. the process is dynamical and the gravity dominates the collapse inside our massive clumps.