Palomar 5 Under Hubble's Eye: Photometric Signatures of Dynamical Evolution

We present a photometric analysis of the disrupting globular cluster Palomar 5, using archival Hubble Space Telescope observations obtained with the ACS Wide Field Channel. To our knowledge, this is the first detailed photometric study of Palomar 5 based on ACS/WFC imaging, which until now has been used primarily for proper-motion measurements. The dataset covers a region near the cluster’s center, offset by ≈0.45 r_h (half-light radius), while avoiding the core, allowing us to trace relatively undisturbed stellar populations with minimal crowding. The photometry was fully reduced and calibrated, and a clean color–magnitude diagram (CMD) was constructed after quality cuts were applied. From this CMD, we extract preliminary estimates of the cluster’s mass and luminosity functions via isochrone fitting, and place constraints on its binary-star population. In addition, we cross-matched our catalog with Gaia DR3 to study the proper-motion distribution and evaluate the consistency of stellar membership. Our results provide insights into the internal structure and dynamical evolution of Palomar 5, particularly in the context of its ongoing tidal disruption.