0 Assigned ID: 119 ----- Attempting Submission 1 (Tue Mar 03 16:46:23 GMT 2020) ----- HST Phase I Proposal 119 successfully submitted. Receipt: # 119-1 ----- Attempting Submission 2 (Fri Mar 06 19:31:45 GMT 2020) ----- The metallicities of galaxies scale with stellar mass. Theoretical notions have long held that, in addition to lower star formation rates and efficiencies, the low metallicities of dwarf galaxies reflect their increasing inability to retain metals. This is seen in cosmological simulations where feedback-driven galactic winds transport metals from galaxy disks to large distances, with a steep inverse dependence of the amount of metals lost with galaxy mass. At long last, it is possible to test this framework of stellar feedback and metal loss by actually tracking the metals in real galaxies. We propose to measure the production, distribution, and retention of metals in the stars and in the ISM in a large sample of low-mass, nearby galaxies over the critical mass range where metal loss is predicted to change the most but has yet to be investigated (i.e., 10^6 ~ 10^9 Msun). We will use an innovative technique that couples star formation histories derived from resolved stars with stellar and ISM metallicity constraints. Our program will measure, for the first time in the low-mass galaxy regime, the mean metal retention fraction as a function of galaxy mass, the dispersion on the relationship, and the differences in retention between the stars and the ISM. This ''accounting'' of the metals will provide significant constraints for models that will be far more detailed than global scaling relations with interdependent variables. Such analysis is only possible on nearby galaxies and our archival program capitalizes on the rich datasets available from the HST, supplemented by additional data from the VLA and ground-based observatories. Our program is led by Kristen McQuinn who developed the technique to measure the metal retention fraction in the low-mass galaxy Leo P. McQuinn has deep expertise working with HST imaging data, CMD-fitting techniques, low-mass galaxies, and star formation driven galaxy evolution. Grace Telford, who performed similar analysis on M31 using the PHAT data, will also be a major contributor to the analysis. Julianne Dalcanton, Ben Williams, and Evan Skillman, the architects of a number of programs reconstructing SFHs and age-metallicity relations from resolved stellar populations in nearby galaxies including PHAT, ANGST, and ANGRRR, provide additional support on resolved stellar populations and star formation histories (SFHs). They will also provide oversight of the high-level science products, ensuring our deliverables are created uniformly with existing data products in the archive on nearby galaxies. Liese van Zee and John Cannon, both leaders in HI data on nearby galaxies, will provide expertise on the HI content, gas rotation curves, and dynamical masses of the sample. Andrey Kravstov contributes significant experience with galaxy simulations and wind models. Xavier Prochaska, Joe Burchett, and John Chisholm bring deep knowledge of baryon flows in and around galaxies, including the CGM, and galactic winds, and provide additional perspectives on where lost metals may reside. Andrew Dolphin is the developer of the DOLPHOT photometry package and the CMD fitting technique MATCH to be used in the analysis. Several members of our team, including Danielle Berg, Liese van Zee, and Evan Skillman, are leading experts on gas-phase abundances in low-mass galaxies. Our team is highly productive and provides both deep skills and well-rounded science expertise to support a comprehensive study of the distribution of metals in low-mass galaxies. Galaxies 0 Regular false false false false false SUPPORTED