Invited Presentation

Dense core properties and star formation in the Infrared Dark clouds

Author(s):

Presenter: Satoshi Ohashi (The University of Tokyo)

High-mass star formation is one of the most outstanding issues in astronomy. The formation process of these stars is still obscure compared with low-mass star formation.
High-mass stars form in crowded environments (clusters) at large distances ($\gtrsim2$ kpc), making difficult to resolve individual objects in clusters. Another difficulty is their very short prestellar phase in spite of the fact that revealing the prestellar phase is very important to investigate high-mass star-forming processes.
Therefore, we have performed a dense core survey toward the Infrared Dark Cloud G14.225-0.506 at 3 mm continuum emission with ALMA high resolution observations and we identified 48 dense cores.
Through virial analysis using the ALMA N2H+ and VLA/Effelsberg NH3 molecular line data, we found a decreasing trend in the virial parameter with decreasing scales from filaments to clumps, and then to cores.
However, we find no massive prestellar or protostellar cores. Therefore, high-mass stars may be formed in the prestellar cores by accreting a significant amount of gas from the surrounding medium. Another possibility is that low-mass YSOs become massive by accreting from their parent cores that are fed by filaments. These two possibilities might be consistent with the scenario of global hierarchical collapse.

I also would like to intorduce our recent ALMA work on dense core propoeties in other IRDCs.