Updated 1430223003 Assigned ID: 2248 ----- Attempting Submission 1 (Fri Apr 09 21:08:01 GMT 2021) ----- HST Phase I Proposal 2248 successfully submitted. Receipt: # 2248-1 ----- Attempting Submission 2 (Fri Apr 09 23:55:57 GMT 2021) ----- HST's resolution opened the study of stellar cluster morphology to observed populations in galaxies throughout the Local Volume and beyond. The structure of stellar clusters is expected to be intimately linked to the physical conditions of their birthplace and to their subsequent path through a host galaxy. Models have had success predicting the cluster mass-radius relation (MRR). However, getting the details right requires dedicated new work from the observational side because extragalactic samples of relevant measurements remain scant and open to improvement in mass/age estimation. There now exists droves of panchromatic HST imaging with WFC3/UVIS for representative samples of typical star-forming nearby galaxies, with the two principal efforts at relevant distances being LEGUS and PHANGS-HST. Even so, a comprehensive investigation into cluster morphology remains unrealized. We now propose such an Archival HST study, aiming to revolutionize the understanding of environmentally-driven MRR dependencies and propel the next generation of simulations with new, fine-grained constraint. Capitalizing on two Legacy surveys, we will analyze ~60,000-70,000 clusters, probing all environments with dramatically increased statistical rigor, allowing for aggregation of samples binned on such local properties (which we have already opitmally determined). We will create and publish/release a cluster catalog with improved structural fits and (age, mass) for use by the community, and answer the most pressing open questions emerging from theoretical modeling of cluster formation and evolution. Dr. David Thilker (PI, JHU) is an expert in multiwavelength observational characterization of star formation in nearby galaxies and radio imaging of neutral hydrogen (HI) in circumgalactic environments. He specializes in ultraviolet imaging from HST and GALEX, with emphasis on star formation occurring at low density. He is credited with the discovery of extended UV disks (XUV disks). Dr. Thilker has extensive experience with PSF fitting, and clump based photometry. Rupali Chandar is an expert at dealing with stellar population and star clusters in nearby star-forming galaxies, particularly using HST observations. Sinan Deger is a postdoctoral researcher specializing in star formation in both nearby and distant galaxies, analysis of morphological features on both the galactic and resolved stellar population level, and the applications of state of the art machine learning techniques in astronomy research. Simon Glover is a theorist who has extensive experience with numerical simulations of the cold ISM and with the production of synthetic observations. He will assist with the theoretical interpretation of the observations and with the comparison of observations with simulations. Ralf Klessen is full professor for theoretical astrophysics at Heidelberg University. His research interests focus on the formation of stars at present days and inthe early universe, on the dynamics of the interstellar medium, on astrophysical turbulence, and on the development of numerical methods for computational astrophysics. Diederik Kruijssen is an expert in the multi-wavelength and theoretical studies of star formation, stellar feedback, and star cluster formation and evolution. Janice Lee is an expert on star formation in nearby galaxies, and ground- and space-based observations of galaxies spanning from the UV to the IR. She is PI of the PHANGS-HST and PHANGS-JWST Treasury programs. Adam Leroy is an expert on dust molecular gas and dust in galaxies, and will contribute to the comparison with ALMA and scientific interpretation of results. Adam has experience with ISM feature identification via image segmentation and the combined use of dust and CO emission to trace molecular gas in the Milky Way, the Local Group, and nearby galaxies. Erik Rosolowsky specializes in using image processing methods to characterizing the structure in the interstellar medium and relate that structure to the regulation of star formation. He and his research group have developed the pyCPROPS algorithm for measuring molecular cloud properties, FilFinder for simple characterization of filamentary structures in two- and three-dimensions, and TurbuStat for measuring the properties of turbulence from images of the ISM. Eva Schinnerer's research experience covers the analysis of optical to radio observational data of nearby and distant star-forming galaxies. She is an expert in the analysis of molecular gas observations and large-scale dynamics. All members of the team will participate at varying degrees in the analysis and paper preparation. Galaxies 0 Regular false false false false true SUPPORTED