English

A Pristine View of Galactic Globular Clusters and their Peripheries: Omega Centauri

Astrophysics of Galaxies 2025-02-04 v1

Abstract

The central regions of the globular cluster Omega Centauri (ω\omega Cen) have been extensively studied, but its outer regions and tidal structure have been less so. Gaia's astrometry uncovered substantial tidal substructure associated with ω\omega Cen, yet the lack of chemical tagging makes these associations tenuous. In this paper, we utilise the Gaia-Synthetic CaHK-band photometry, metallicities from the Pristine survey and Gaia's astrometry to explore up to a clustercentric radius of 5 degrees from ω\omega Cen. We identify ω\omega Cen-like stars based on proper motion, colour-magnitude and colour-colour space, exploring the morphology, and stellar populations of the outer regions. Our probabilistic approach recovers the tidal tails of ω\omega Cen, and we investigate the metallicity distribution of ω\omega Cen ranging from a radius of 15 arcmin to the tidal radius, and beyond into the tidal tails. We present (1) two components between 15 arcmin and tidal radius at -1.83 and -1.45 dex which are also the dominant populations within 15 arcmin, and (2) the first evidence that the same two populations in the outer regions of the cluster are present outside the tidal radius and into the tidal tails. These populations are mixed about the stream, and are typically amongst the faintest stars in our sample; all indicating that the tidal tails are made of tidally stripped ω\omega Cen stars.

Keywords

Cite

@article{arxiv.2502.01135,
  title  = {A Pristine View of Galactic Globular Clusters and their Peripheries: Omega Centauri},
  author = {P. B. Kuzma and M. N. Ishigaki},
  journal= {arXiv preprint arXiv:2502.01135},
  year   = {2025}
}

Comments

Accepted for publication in MNRAS. 11 pages, 9 figures, and the underlying catalogue used can be found at DOI:10.5281/zenodo.14791430

R2 v1 2026-06-28T21:30:06.360Z