The Outer Envelopes of Globular Clusters. II. NGC 1851, NGC 5824 and NGC 1261

Abstract

We present a second set of results from a wide-field photometric survey of the environs of Milky Way globular clusters. The clusters studied are NGC 1261, NGC 1851 and NGC 5824: all have data from DECam on the Blanco 4m telescope. NGC 5824 also has data from the Magellan Clay telescope with MegaCam. We confirm the existence of a large diffuse stellar envelope surrounding NGC 1851 of size at least 240 pc in radius. The radial density profile of the envelope follows a power-law decline with index $\gamma =-1.5\pm 0.2$ and the projected shape is slightly elliptical. For NGC 5824 there is no strong detection of a diffuse stellar envelope, but we find the cluster is remarkably extended and is similar in size (at least 230 pc in radius) to the envelope of NGC 1851. A stellar envelope is also revealed around NGC 1261. However, it is notably smaller in size with radius $\sim$105 pc. The radial density profile of the envelope is also much steeper with $\gamma =-3.8\pm 0.2$. We discuss the possible nature of the diffuse stellar envelopes, but are unable to draw definitive conclusions based on the current data. NGC 1851, and potentially NGC 5824, could be stripped dwarf galaxy nuclei, akin to the cases of $\omega$ Cen, M54 and M2. On the other hand, the different characteristics of the NGC 1261 envelope suggest that it may be the product of dynamical evolution of the cluster.

18 pages, 11 figures, accepted to MNRAS

References in corpus (18)

• The Dartmouth Stellar Evolution Database
• Beasts of the Southern Wild: Discovery of nine Ultra Faint satellites in the vicinity of the Magellanic Clouds
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
• The ACS Survey of Galactic Globular Clusters. III. The Double Subgiant Branch of NGC 1851
• An abundance analysis of bright giants in the globular cluster NGC 1851
• Discovery of a New, Polar-Orbiting Debris Stream in the Milky Way Stellar Halo
• A 22 Degree Tidal Tail for Palomar 5
• A large C+N+O abundance spread in giant stars of the globular cluster NGC 1851
• Tracing Sagittarius Structure with SDSS and SEGUE Imaging and Spectroscopy
• The outer halo globular cluster system of M31 - I. The final PAndAS catalogue
• Contribution of stripped nuclear clusters to globular cluster and ultra-compact dwarf galaxy populations
• CNO abundances in the globular clusters NGC 1851 and NGC 6752
• The orbits of 48 globular clusters in a Milky-Way-Like Barred Galaxy
• The halo+cluster system of the Galactic globular cluster NGC1851
• A search for stellar tidal debris of defunct dwarf galaxies around globular clusters in the inner Galactic halo
• The Effect of Orbital Eccentricity on the Dynamical Evolution of Star Clusters
• Stellar Substructures around the Hercules Dwarf Spheroidal Galaxy
• Accretion in action: phase space coherence of stellar debris and globular clusters in Andromeda's South-West Cloud

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• Chemical composition of the outer halo globular cluster Palomar 15