0 Assigned ID: 948 ----- Attempting Submission 1 (Fri Mar 06 23:39:56 GMT 2020) ----- HST Phase I Proposal 948 successfully submitted. Receipt: # 948-1 ----- Attempting Submission 2 (Sat Mar 07 00:06:50 GMT 2020) ----- HST Phase I Proposal 948 successfully submitted. Receipt: # 948-2 ----- Attempting Submission 3 (Sat Mar 07 00:38:05 GMT 2020) ----- The Galactic center offers us an opportunity to study star formation in an extreme environment at a level of detail not accessible in any other galaxy. However, it is current unclear how the combination of high gas densities, strong cloud turbulence, radiation fields, and tidal shear in this environment affect star formation. It has been postulated that star formation can be triggered by molecular cloud collisions among the X1 and X2 galactic orbital families, or more recently, by tidal compression of clouds on a particular orbit that forms a "conveyor belt of star formation". These two theories make different predictions regarding the orbits of molecular clouds and sites of star formation at the Galactic Center. We propose to test these models by measuring the proper motions of young star clusters in the central 100 pc of the Milky Way, which due to their young age, trace the orbit of their natal clouds. We will leverage 34 orbits of archival HST WFC3-IR observations and the GAIA DR2 catalog to definitively measure the absolute proper motion of 3 young clusters: the Arches and Quintuplet cluster, and a newly discovered candidate cluster. Their motion will allow us to distinguish between these star formation scenarios, yielding insight into the physical processes and time scales involved in star formation at the Galactic Center. Our team consists of members who, together, have decades of astrometry and HST experience. PI Do, Co-I Lu, and Co-I Ghez have all been PI of previous successful HST astrometry programs with WFC3-IR. Co-PI Hosek and Co-I Lu have previously worked on relative astrometeric measurements of the Arches and Quintuplet clusters with HST and from the ground. Our team has strong expertise in high-precision astrometry and the construction of reference frames, including that of measuring stellar orbits around the supermassive black hole at the Galactic center. Scientifically, our team has also been studying the star formation at the Galactic center for decades (including Co-I Morris who has developed some of the models we are testing with this program). Co-PI Hosek will lead the extraction of HST astrometry from archival HST images, build a reference frame with GAIA + HST, and measure proper motions. PI-Do will provide oversight for the project and aid in the construction of the reference frame. Co-I's Lu, Morris, and Ghez will provide consultation on the astrometry and scientific interpretations. All team members will participate in publishing the results. For more details, please see our Analysis Plan. Stellar Populations and the Interstellar Medium 0 Regular false false false false false SUPPORTED