Halo intruders in the Galactic bulge revealed by HST and Gaia: the globular clusters Terzan 10 and Djorgovski 1

Understand

The low-latitude globular clusters Terzan 10 and Djorgovski 1 are vprojected in the Galactic bulge, in a Galactic region highly affected by extinction.

• A discrepancy of a factor of ~2 exists in the literature in regards to the distance determination of these clusters.
• We revisit the colour-magnitude diagrams (CMDs) of these two globular clusters with the purpose of disentangling their distance determination ambiguity and, for the first time, of determining their orbits to identify whether or not they are part of the bulge/bar region.
• We use Hubble Space Telescope CMDs, with the filters F606W from ACS and F160W from WFC3 for Terzan 10, and F606W and F814W from ACS for Djorgosvski~1, and combine them with the proper motions from Gaia Date Release 2.