0 Assigned ID: 1571 ----- Attempting Submission 1 (Wed Apr 07 20:44:00 GMT 2021) ----- HST Phase I Proposal 1571 successfully submitted. Receipt: # 1571-1 ----- Attempting Submission 2 (Fri Apr 09 18:32:42 GMT 2021) ----- We propose to combine Gaia- and HST-based orbital histories with HST-based star formation histories (SFHs) for five classical Milky Way (MW) satellites (M* = 10^5-10^7 Msun; Carina, Fornax, Leo I, Leo II, Phoenix I) to quantify the processes by which low-mass satellites galaxies quench. Specifically, we will correlate the timing and frequency of orbital parameters (e.g., location in halo, velocity, number of orbits) with star formation episodes (bursts, dips, overall decline) to provide data-driven insight into how low-mass satellites transition from star-forming to quenched as they orbit within the halo of a massive galaxy. These five classical MW satellites have exquisite 6D phase space information (3D position + 3D velocity) from Gaia and HST, and well-populated color-magnitude diagrams (CMDs) from archival HST programs, allowing for precise SFH recovery over the past several Gyr. In the era of precise SFHs and orbital histories, this program will establish the framework necessary to move beyond two point comparisons of infall time and quenching time commonly used in studies of low-mass galaxy quenching. Through a joint analysis of detailed SFHs and precise orbital histories, we will paint a clear picture of where, when, and how low-mass MW satellite galaxies quench. This program leverages substantial ongoing HST investments aimed at measuring SFHs and proper motions (PMs) of Local Group dwarf galaxies. The results and infrastructure established and published by this program will serve as important templates for quantifying the quenching process as more low-mass satellite galaxy SFHs and PMs are measured by HST and JWST. PI Patel is an expert on the dynamical modeling of satellite galaxies in the Local Group. She has used Gaia- and HST- based proper motion measurements to calculate the orbits of Andromeda, the Magellanic Clouds, and nearly twenty of the Milky Way's dwarf satellite galaxies. She has also been involved with several successful programs in recent HST cycles to obtain first, second, and even third epoch imaging of Local Group galaxies. PI Patel also has extensive experience using the dynamics of satellite galaxies to constrain the dark matter mass of their hosts. Co-I Weisz is an expert on using deep HST images to reconstruct the star formation histories of dwarf galaxies. He has led many successful HST programs over the last decade focusing on satellite galaxies of the Milky Way and Andromeda, isolated dwarf galaxies, and even globular clusters. Co-I Weisz and Co-I Savino have extensive knowledge of the CMD-fitting techniques and stellar models that will be implemented to derive star formation histories in this program. Galaxies Stellar Populations and the Interstellar Medium 0 Regular false false false false false SUPPORTED