Tails and streams around the Galactic globular clusters NGC1851, NGC1904, NGC2298 and NGC2808

TL;DR

This study uses deep DECam imaging to analyze the outskirts of four Galactic globular clusters, revealing stellar tails, surrounding overdensities, and potential connections to halo substructures or accreted dwarf galaxies.

Contribution

It provides new detailed observations of stellar tails and surrounding structures around these clusters, suggesting possible origins related to Galactic accretion events.

Findings

Detection of stellar tails beyond King radii in all clusters

Identification of a large stellar system at ~17 kpc possibly linked to Monoceros

Evidence of complex substructures around the clusters

Abstract

We present DECam imaging for the peculiar Galactic globular clusters NGC1851, NGC1904 (M79), NGC2298 and NGC2808. Our deep photometry reveals that all the clusters have an important contribution of stars beyond their King tidal radii and present tails with different morphologies. We have also explored the surroundings of the clusters where the presence of the Canis Major overdensity and/or the low Galactic latitude Monoceros ring at d~8kpc is evident. A second stellar system is found at d~17kpc and spans at least 18deg x 15deg in the sky. As one of the possible scenarios to explain that feature, we propose that the unveiled system is part of Monoceros explained as a density wave moving towards the outer Milky Way. Alternatively, the unveiled system might be connected with other known halo substructures or associated with the progenitor dwarf galaxy of NGC1851 and NGC1904, which are widely considered accreted globular clusters.