Euclid: Early Release Observations -- The star cluster systems of the Local Group dwarf galaxies IC 10 and NGC 6822

Abstract

Star clusters are valuable indicators of galaxy evolution, offering insights into the buildup of stellar populations across cosmic time. Understanding intrinsic star cluster populations of dwarf galaxies is particularly important given their role in the hierarchical growth of larger systems. Using Euclid Early Release Observation data, we study star clusters in two star-forming dwarf irregulars in the Local Group, NGC 6822 and IC 10 [$M_{\star }\sim$ (1--4) $\times 10^8{M}_{\odot }$]. With Euclid, clusters are resolved into individual stars across the main bodies and haloes of both galaxies. Visual inspection of $I_E$ images uncovers 30 new cluster candidates in NGC 6822 and 16 in IC 10, from compact to extended clusters. We re-evaluate literature candidates, producing combined catalogues of 52 (NGC 6822) and 71 (IC 10) clusters with confidence-based classifications. We present homogeneous photometry in $I_E$, $Y_E$, $J_E$, $H_E$, and archival UBVRI data, alongside size measurements and properties from BAGPIPES SED fitting. Synthetic cluster injection shows our sample is $\sim 50$% complete to $M\lesssim 10^3{M}_{\odot }$ for ages $\lesssim 100$ Myr, and to $M\lesssim 3\times 10^4{M}_{\odot }$ for $\sim 10$ Gyr. IC 10 has more young clusters than NGC 6822, extending to higher masses, consistent with its starburst nature. Both dwarfs host several old massive ($\gtrsim 10^5{M}_{\odot }$) clusters, including an exceptional $1.3\times 10^6{M}_{\odot }$ cluster in NGC 6822's outskirts. In NGC 6822, we identify a previously undetected, old, extended cluster ($R_h=12.4\pm 0.11$ pc). Using well-defined criteria, we identify 11 candidate GCs in NGC 6822 and eight in IC 10. Both galaxies have high specific frequencies ($S_N$) but remain consistent with known GC scaling relations at low luminosity [abridged].

Accepted by A&A

References in corpus (50)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• Euclid. I. Overview of the Euclid mission
• High-resolution mass models of dwarf galaxies from LITTLE THINGS
• What is a globular cluster? An observational perspective
• Age Determination of Six Intermediate-age SMC Star Clusters with HST/ACS
• The mass function of young star clusters in spiral galaxies
• Probing the role of the galactic environment in the formation of stellar clusters; using M83 as a test bench
• Constraining the thermally pulsing asymptotic giant branch phase with resolved stellar populations in the Large Magellanic Cloud
• Gaia early DR3 systemic motions of Local Group dwarf galaxies and orbital properties with a massive Large Magellanic Cloud
• ASteCA - Automated Stellar Cluster Analysis
• The outer halo globular cluster system of M31 - I. The final PAndAS catalogue
• Old and young stellar populations in DustPedia galaxies and their role in dust heating
• Euclid. III. The NISP Instrument
• Satellite Dwarf Galaxies in a Hierarchical Universe: The Prevalence of Dwarf-Dwarf Major Mergers
• Globular Cluster Systems in Nearby Dwarf Galaxies: I. HST/ACS Observations and Dynamical Properties of Globular Clusters at Low Environmental Density
• Euclid. II. The VIS Instrument
• ACS imaging of star clusters in M51. I. Identification and radius distribution
• The Spatial Relation between Young Star Clusters and Molecular Clouds in M 51 with LEGUS
• Globular clusters in the outer halo of M31: the survey
• PHAT Stellar Cluster Survey. II. Andromeda Project Cluster Catalog
• Red Supergiant Stars as Cosmic Abundance Probes: KMOS Observations in NGC 6822
• Kinematics and simulations of the stellar stream in the halo of the Umbrella Galaxy
• ELVES II: GCs and Nuclear Star Clusters of Dwarf Galaxies; The Importance of Environment
• Sizes and Shapes of Young Star Cluster Light Profiles in M83
• Star Cluster Catalogs for the LEGUS Dwarf Galaxies
• Euclid: Early Release Observations -- Programme overview and pipeline for compact- and diffuse-emission photometry
• The minimum metallicity of globular clusters and its physical origin -- implications for the galaxy mass-metallicity relation and observations of proto-globular clusters at high redshift
• On the distance and reddening of the starburst galaxy IC10
• Clearing the hurdle: The mass of globular cluster systems as a function of host galaxy mass
• A New Cepheid Distance Measurement and Method for NGC 6822
• The chemical composition of globular clusters in the Local Group
• Gas-rich, field ultra-diffuse galaxies host few globular clusters
• Bright, Relatively Isolated Star Clusters in PHANGS-HST Galaxies: Aperture Corrections, Quantitative Morphologies, and Comparison with Synthetic Stellar Population Models
• Solo dwarfs II: The stellar structure of isolated Local Group dwarf galaxies
• Euclid: Early Release Observations -- Deep anatomy of nearby galaxies
• The inefficiency of satellite accretion in forming extended star clusters
• Spectroscopic Confirmation of the Sixth Globular Cluster in the Fornax Dwarf Spheroidal Galaxy
• The Globular Cluster System of NGC 6822
• Euclid: Early Release Observations -- Globular clusters in the Fornax galaxy cluster, from dwarf galaxies to the intracluster field
• The Star Cluster System in the Local Group Starburst Galaxy IC 10
• STEP Survey II: Structural Analysis of 170 star clusters in the SMC
• DDO216-A1: a central globular cluster in a low-luminosity transition type galaxy
• The Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER). IV. Star Cluster Catalog
• A panoramic view of the Local Group dwarf galaxy NGC 6822
• A state-of-the-art analysis of the dwarf irregular galaxy NGC 6822
• Rubin Observatory LSST Stars Milky Way and Local Volume Star Clusters Roadmap
• PHANGS-HST: Globular Cluster Systems in 17 Nearby Spiral Galaxies
• Euclid: Star clusters in IC 342, NGC 2403, and Holmberg II

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