Gas Excitation, Chemistry, and Dust in Super Star Clusters

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The formation of giant star clusters forms a key part of the history of the universe and our own Milky Way galaxy. Giant clusters contain the most massive and luminous stars in existence. These massive stars rapidly produce chemical elements in their interiors. Strong winds and intense radiation fields from the stars then enrich and disperse these elements into surrounding clouds. The affected clouds in turn determine the future of the cluster in ways that are as yet not well understood. The Atacama Large Millimeter/Submillimeter Array (ALMA) allows high-fidelity imaging of emission from spectral lines of molecules. With ALMA, it is now possible to observe individual gas clouds in local galaxies. The goals of this research are to observe and model the effects of massive stars on gas near young star clusters. The project provides for training of graduate and undergraduate students, and it will establish more effective links to the local community by improving bilingual outreach.The investigators will use ALMA to measure gas and dust properties in molecular clouds near the youngest massive clusters in local galaxies. Using high resolution images of submillimeter spectral lines of carbon monoxide and other molecules, chemical characteristics of molecular clouds forming super star clusters will be defined. Combined modeling of excitation and chemistry within these clouds will be done using the code, CLOUDY. Observations of molecular lines and dust currently scheduled to be observed at ALMA will be analyzed, reduced, and modeled. Submillimeter spectral energy distributions will be used to estimate the dust content and enrichment by the clusters. Kinematics and excitation together will allow a three-dimensional view of internal cloud structure. This program is the detailed study of gas on cluster scales, with the goal of putting together a comprehensive picture, morphological and dynamical, of how the cluster interacts with the gas and dust of its natal cloud. The results of the analyses will be published, and data products, including line cubes and their derivatives, and grids of line ratios from the modeling, will be made available to the astronomical community.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.