Is Fornax 4 the nuclear star cluster of the Fornax dwarf spheroidal galaxy?

Abstract

Fornax 4 is the most distinctive globular cluster in the Fornax dwarf spheroidal. Located close to the centre of the galaxy, more metal-rich and potentially younger than its four companions (namely, Fornax clusters number 1, 2, 3 and 5), it has been suggested to have experienced a different formation than the other clusters in the galaxy. Here we use HST/WFC3 photometry to characterize the stellar population content of this system and shed new light on its nature. By means of a detailed comparison of synthetic horizontal branch and red giant branch with the observed colour-magnitude diagrams, we find that this system likely hosts stellar sub-populations characterized by a significant iron spread up to $\Delta$[Fe/H]$\sim$0.4 dex and possibly by also some degree of He abundance variations $\Delta$Y$\sim 0.03$. We argue that this purely observational evidence, combined with the other peculiarities characterizing this system, supports the possibility that Fornax 4 is the nuclear star cluster of the Fornax dwarf spheroidal galaxy. A spectroscopic follow-up for a large number of resolved member stars is needed to confirm this interesting result and to study in detail the formation and early evolution of this system and more in general the process of galaxy nucleation.

arXiv commentAccepted for publication in MNRAS. 12 pages, 11 figures

References in corpus (71)

• The observed properties of dwarf galaxies in and around the Local Group
• Cosmic-Ray Rejection by Laplacian Edge Detection
• A large stellar evolution database for population synthesis studies. I. Scaled solar models and isochrones
• Multiple populations in globular clusters. Lessons learned from the Milky Way globular clusters
• Na-O Anticorrelation and HB. VII. The chemical composition of first and second-generation stars in 15 globular clusters from GIRAFFE spectra
• A large stellar evolution database for population synthesis studies. II. Stellar models and isochrones for an alpha-enhanced metal distribution
• Na-O Anticorrelation and HB. VIII. Proton-capture elements and metallicities in 17 globular clusters from UVES spectra
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. I. Overview of the Project and Detection of Multiple Stellar Populations
• The ACS Survey of Galactic Globular Clusters. XII. Photometric Binaries along the Main-Sequence
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IX. The Atlas of Multiple Stellar Populations
• Spectroscopic and Photometric evidence of two stellar populations in the Galactic Globular Cluster NGC6121 (M4)
• Formation of omega Centauri from an ancient nucleated dwarf galaxy in the young Galactic disc
• An HST Census of Nuclear Star Clusters in Late-Type Spiral Galaxies: I. Observations and Image Analysis
• Masses of star clusters in the nuclei of bulge-less spiral galaxies
• Detailed abundances of a large sample of giant stars in M 54 and in the Sagittarius nucleus
• The nucleus of the Sagittarius dSph galaxy and M54: a window on the process of galaxy nucleation
• Stellar populations in the nuclei of late-type spiral galaxies
• The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters - XVII. Public Catalogue Release
• Co-evolution of nuclear star clusters, massive black holes and their host galaxies
• Globular Cluster Systems in Nearby Dwarf Galaxies: III. Formation Efficiencies of Old Globular Clusters
• Looking outside the Galaxy: the discovery of chemical anomalies in 3 old Large Magellanic Cloud clusters
• Large scale kinematics and dynamical modelling of the Milky Way nuclear star cluster
• Surface Brightness Profiles and Structural Parameters for Globular Clusters in the Fornax and Sagittarius Dwarf Spheroidal Galaxies
• VLT/UVES Spectroscopy of Individual Stars in Three Globular Clusters in the Fornax Dwarf Spheroidal Galaxy
• Star count density profiles and structural parameters of 26 Galactic globular clusters
• Age as a Major Factor in the Onset of Multiple Populations in Stellar Clusters
• Revised bolometric corrections and interstellar extinction coefficients for the ACS and WFPC2 photometric systems
• Constraints on mass loss and self-enrichment scenarios for the globular clusters of the Fornax dSph
• Stellar populations and star formation histories of the nuclear star clusters in six nearby galaxies
• Constraining the role of star cluster mergers in nuclear cluster formation: Simulations confront integral-field data
• The peculiar Horizontal Branch of NGC 2808
• Double Blue Straggler sequences in GCs: the case of NGC 362
• The Globular Cluster Migratory Origin of Nuclear Star Clusters
• The Search for Multiple Populations in Magellanic Cloud Clusters II: The Detection of Multiple Populations in Three Intermediate-Age SMC Clusters
• The Horizontal Branch in the UV Colour Magnitude Diagrams. II. The case of M3, M13 and M79
• Multiple populations in the old and massive Small Magellanic Cloud globular cluster NGC121
• Multiple stellar populations in Magellanic Cloud clusters. III. The first evidence of an extended main sequence turn-off in a young cluster: NGC1856
• Detailed abundance analysis from integrated high-dispersion spectroscopy: Globular clusters in the Fornax Dwarf Spheroidal
• Nitrogen abundances and multiple stellar populations in the globular clusters of the Fornax dSph
• Self-consistent simulations of Nuclear Cluster formation through Globular Cluster orbital decay and merging
• New insights on the formation of nuclear star clusters
• Nuclear Star Clusters from Clustered Star Formation
• First evidence of fully spatially mixed first and second generations in globular clusters: the case of NGC 6362
• A deep view into the nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. I. Data and stellar population characterization
• The Search for Multiple Populations in Magellanic Cloud Clusters III: No evidence for Multiple Populations in the SMC cluster NGC 419
• Star Clusters in M31. V. Evidence for Self-Enrichment in Old M31 Clusters from Integrated Spectroscopy
• The search for multiple populations in Magellanic Clouds clusters - V. Correlation between cluster age and abundance spreads
• The Search for Multiple Populations in Magellanic Cloud Clusters I: Two Stellar Populations in the Small Magellanic Cloud Globular Cluster NGC 121
• Two-dimensional H_alpha kinematics of bulgeless disk galaxies
• Spectroscopy of Globular Clusters in the Fornax dwarf galaxy
• Insights from the Outskirts: Chemical and Dynamical Properties in the outer Parts of the Fornax Dwarf Spheroidal Galaxy
• The difference in metallicity distribution functions of halo stars and globular clusters as a function of galaxy type: A tracer of globular cluster formation and evolution
• No evidence of mass segregation in the low mass Galactic globular cluster NGC 6101
• The complex nature of the nuclear star cluster in FCC 277
• Four and one more: The formation history and total mass of globular clusters in the Fornax dSph
• The binary fraction in the globular cluster M10 (NGC 6254): comparing core and outer regions
• The bursty star formation history of the Fornax dwarf spheroidal galaxy revealed with the HST
• Constraining nuclear star cluster formation using MUSE-AO observations of the early-type galaxy FCC47
• Variable stars in the Fornax dSph Galaxy. I. The Globular Cluster Fornax 4
• Spectroscopic detection of multiple populations in the ~2 Gyr old cluster Hodge 6 in the LMC
• Deep HST-WFPC2 photometry of NGC 288. II. The Main Sequence Luminosity Function
• Helium enrichment in intermediate-age Magellanic Clouds clusters: towards an ubiquity of multiple stellar populations?
• IC4499 revised: spectro-photometric evidence of small light-element variations
• The puzzle of metallicity and multiple stellar populations in the Globular Clusters in Fornax
• Kron 3: a fourth intermediate age cluster in the SMC with evidence of multiple populations
• Rediscovery of the Sixth Star Cluster in the Fornax Dwarf Spheroidal Galaxy
• Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud IV: Evidence for Multiple Populations in Hodge 11 and NGC 2210
• The double Blue Straggler sequence in NGC2173: a field contamination artefact
• Light element variations within the different age-metallicity populations in the nucleus of the Sagittarius dwarf
• Evidence for a chemical enrichment coupling of globular clusters and field stars in the Fornax dSph
• On the use of the main sequence knee (saddle) to measure globular cluster ages

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• The nucleation fraction of Local Volume galaxies
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