Hierarchical Star Formation in the Magellanic Clouds - a study based on the VMC survey

Modern observations reveal that star formation is a hierarchical process, which occurs on a wide range of length and time scales. This leads to a continuous hierarchy of young stellar structures, including star clusters, associations, and complexes for increasing size/mass and decreasing density. The investigation of hierarchical young stellar structures will provide insight into how star formation is organized across the galaxy and how it is controlled by various physical processes. Based on the VMC survey (VISTA near-infrared YJKs survey of the Magellanic system), we have carried out a comprehensive study of hierarchical star formation in the SMC and in two LMC star-forming complexes. Our work shows that in all three cases the young stars are born with a highly non-uniform spatial distribution; instead, they form significant amount of clumps - young stellar structures. These structures have very irregular morphology, and are organized in a hierarchical, "tree-like" manner. They have a power-law mass/size distribution, and a lognormal surface density distribution. All these phenomena resemble those of a turbulent ISM, and could be inherited from the ISM to the newly formed stars. Thus, our work supports a scenario of hierarchical star formation controlled by turbulence. In this talk, I will also briefly discuss the evolution of hierarchical young stellar structures. 

Sun Ningchen
1st Seminar Room, KIAA-PKU
Friday, March 30, 2018 - 5:00pm to 6:00pm