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AR 16629 (Archival Research)

Mon Jul 15 06:09:08 GMT 2024

Principal Investigator: Imants Platais
PI Institution: The Johns Hopkins University
Investigators (xml)

Title: Probing for astrometric accelerations in the globular cluster NGC 5139
Cycle: 29

Abstract
We will probe astrometric acceleration - one of the most challenging measurement with HST. Assuming that the main source of astrometric acceleration are binaries containing the star and a dim or invisible component, there are exciting prospects as to what such a component could be. The 12-year-long and regularly-scheduled WFC3/UVIS calibration programs provide a unique opportunity to do that now. To make it even more compelling, the target of this program is the core of NGC 5139, the most enigmatic Galactic globular cluster. This project might have potential synergy with the ongoing Gaia observations, if there are common objects revealing signs of acceleration. We will also calculate new relative proper motions which are expected to have superior accuracy and helping to better characterize the internal velocity dispersion.