Koraljka Muzic

Kora Muzic (CENTRA, University of Lisbon, Portugal)



With masses between those of stars and planets, brown dwarfs represent a critical link between the two classes of objects. Understanding their origin has been a major motivation for recent deep studies of star-forming regions and clusters as well as a driver for the development of state-of-the-art simulations. Deep surveys show that brown dwarfs are a ubiquitous outcome of star formation, with about 0.2-0.5 sub-stellar objects formed for each star. One of the big questions in brown dwarf studies is whether the birth environment affects their formation efficiency, as predicted in several formation theories. The expectation is that high gas or stellar densities, as well as the presence of massive OB stars, may be factors that boost the incidence of newly formed brown dwarfs with respect to stars. To test these scenarios, we compare the findings of our decade-long deep survey SONYC, in which we characterized sub-stellar populations of several nearby star-forming regions, with the results of our new investigations of sub-stellar objects in the massive young clusters RCW 38 and NGC 2244, characterized by drastically different star-forming environments. Here I will present the current status of young brown dwarf studies, compare the low-mass Initial Mass Functions in a variety of Milky Way environments, and outline the implications of these results for our understanding of sub-stellar formation processes.