How do Density, Feedback, Gas Dynamics, and Magnetic Fields affect Star Formation within Clusters?

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Understanding the origins of stars is a major undertaking in modern astrophysics. Stars form deep within vast molecular clouds across the Galaxy, as the result of a complex interplay between their gas densities and motions, the local magnetic fields, and energy feedback from nearby young stars on different scales. In particular, most stars, and especially those of higher mass, actually form within embedded clusters, groups of 30-1000+ protostars gravitationally bound to each other and their associated gas. Such environments are complicated by the close proximity of so many nearby protostars that impact their surroundings. Nevertheless, a general understanding of star formation requires a thorough analysis of the physical factors within such environments since they lead to stars of all known mass. Indeed, our Sun and its planetary system arguably formed within such a clustered environment. We propose two projects that delve into the origins of stars within clusters using exciting new observations and techniques. First, we will obtain a full census of embedded clusters found in the molecular clouds nearest to the Sun, using mid-infrared data from the soon-to-be-launched James Webb Space Telescope and submillimetre data from the Atacama Large Millimetre Array that together will reveal clearly their youngest protostar populations. To help us find these objects, we will also develop a new machine learning-based classification algorithm. The resulting numbers will be compared to high-resolution maps of the distributions of gas across nearby clouds obtained using data from the Herschel Space Observatory at far-infrared wavelengths. Indeed, a previous examination of these quantities revealed a strong correlation between them but it must be tested within the most extreme environments of embedded clusters. Second, we will examine the motions of the dense gas and the magnetic fields in the same clusters, specifically the larger filamentary structures in clouds that host them and the smaller ones within them. The line emission from ammonia, a great tracer of dense gas motions, toward many nearby clusters has been already mapped from the Green Bank Telescope, and polarization data, a great tracer of magnetic field direction, from the James Clerk Maxwell Telescope in the same locations will be soon also available. The analysis will be carried out using new techniques that isolate gas flows within filaments. Indeed, the combination of these datasets will enable new connections to be made between gas velocity gradients and magnetic field directions and strengths. Given their common targets, the two projects are complementary and together will make significant contributions to understanding star formation in general. These projects will be the basis of the PhD dissertations of two graduate students, and will help maintain Canada's global leadership in this field over the next five years and beyond.