Discovery of a new nearby globular cluster with extreme kinematics located in the extension of a halo stream

Dante Minniti, José G. Fernández-Trincado, Matiás Gómez, Leigh C. Smith, Philip W. Lucas, Rodrigo Contreras Ramos

Research output: Contribution to journalArticlepeer-review

Abstract

Context. We report the discovery of VVV-CL160, a new nearby globular cluster (GC) with extreme kinematics, located in the Galactic plane at l = 10.1477 deg, b = 0.2999 deg. Aims. We aim to characterize the physical properties of this new GC and place it in the context of the Milky Way, exploring its possible connection with the known GC NGC 6544 and with the Hrid halo stream. Methods. VVV-CL160 was originally detected in the VISTA Variables in the Viá Láctea (VVV) survey. We use the proper motions (PMs) from the updated VVV Infrared Astrometric Catalog (VIRAC2) to select GC members and make deep near-infrared color-magnitude diagrams to study the cluster properties. We also fit King models to the decontaminated sample to determine the GC structural parameters. Results. VVV-CL160 has an unusually large PM for a Galactic GC as measured with VIRAC2 and Gaia EDR3: μα cos (δ) =-2.3 ± 0.1 mas yr-1 and μδ =-16.8 ± 0.1 mas yr-1. The kinematics are similar to those of the known GC NGC 6544 and the Hrid halo stream. We estimate a reddening of E(J-K) = 1.95 mag and an extinction of AK = 1.40 mag for VVV-CL160. We also measure a distance modulus of (m-M) = 13.01 mag and a distance of D⊙ = 4.0 ± 0.5 kpc. This places the GC at z = 29 pc above the Galactic plane and at a galactocentric distance of RG = 4.2 kpc. We also measure a metallicity of [Fe/H] =-1.4 ± 0.2 dex for an adopted age of t = 12 Gyr; King model fits of the PM-decontaminated sample reveal a concentrated GC, with core radius rc = 22.8″ and tidal radius rt = 50′. We also estimate the absolute magnitude in the near-infrared of MK =-7.6 mag, equivalent to an optical absolute magnitude of MV =-5.1 mag. We also explore the possible association of this new GC with other GCs and halo streams. Conclusions. Based on the locations and kinematics, we suggest that VVV-CL160, along with NGC 6544, may be associated with the extension of the Hrid halo stream.

Original languageEnglish
Article numberL11
JournalAstronomy and Astrophysics
Volume650
DOIs
Publication statusPublished - 1 Jun 2021

Keywords

  • Galaxies: Dwarf
  • Galaxy: Bulge
  • Galaxy: Halo
  • Globular clusters: General
  • Globular clusters: Individual: NGC 6544
  • Globular clusters: Individual: VVV-CL160

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint

Dive into the research topics of 'Discovery of a new nearby globular cluster with extreme kinematics located in the extension of a halo stream'. Together they form a unique fingerprint.

Cite this