A deep Large Binocular Telescope view of the Canes Venatici I dwarf galaxy

Abstract

We present the first deep color-magnitude diagram of the Canes Venatici I (CVnI) dwarf galaxy from observations with the wide field Large Binocular Camera on the Large Binocular Telescope. Reaching down to the main-sequence turnoff of the oldest stars, it reveals a dichotomy in the stellar populations of CVnI: it harbors an old (> 10 Gyr), metal-poor ([Fe/H] ~ -2.0) and spatially extended population along with a much younger (~ 1.4-2.0 Gyr), 0.5 dex more metal-rich, and spatially more concentrated population. These young stars are also offset by 64_{-20}^{+40} pc to the East of the galaxy center. The data suggest that this young population, which represent ~ 3-5 % of the stellar mass of the galaxy within its half-light radius, should be identified with the kinematically cold stellar component found by Ibata et al. (2006). CVnI therefore follows the behavior of the other remote MW dwarf spheroidals which all contain intermediate age and/or young populations: a complex star formation history is possible in extremely low-mass galaxies.

arXiv comment4 pages, 3 figures, accepted for publication in ApJL. Minor changes, conclusions unchanged

References in corpus (12)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets
• The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem
• The SDSS View of the Palomar-Green Bright Quasar Survey
• The Observed properties of Dark Matter on small spatial scales
• A New Milky Way Dwarf Satellite in Canes Venatici
• The ACS Survey of Galactic Globular Clusters. II. Stellar Evolution Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch Models
• A Keck/DEIMOS spectroscopic survey of faint Galactic satellites: searching for the least massive dwarf galaxies
• A Dynamical Fossil in the Ursa Minor Dwarf Spheroidal Galaxy
• Globular Cluster Distances from RR Lyrae Stars
• The blue plume population in dwarf spheroidal galaxies: genuine blue stragglers or young stellar population?
• A near zero velocity dispersion stellar component in the Canes Venatici dwarf spheroidal galaxy

Cited by in corpus (41)

• Star Formation Histories, Abundances and Kinematics of Dwarf Galaxies in the Local Group
• Accurate masses for dispersion-supported galaxies
• Eight New Milky Way Companions Discovered in First-Year Dark Energy Survey Data
• A comprehensive Maximum Likelihood analysis of the structural properties of faint Milky Way satellites
• The Star Formation Histories of Local Group Dwarf Galaxies I. Hubble Space Telescope / Wide Field Planetary Camera 2 Observations
• The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies
• The Local Group on FIRE: Dwarf galaxy populations across a suite of hydrodynamic simulations
• Local-Group tests of dark-matter Concordance Cosmology: Towards a new paradigm for structure formation
• A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters
• The Star Formation Histories of Local Group Dwarf Galaxies II. Searching For Signatures of Reionization
• The dynamics of isolated Local Group galaxies
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. IV. Alpha Element Distributions in Milky Way Dwarf Satellite Galaxies
• Willman 1 - a probable dwarf galaxy with an irregular kinematic distribution
• Local Group Dwarf Spheroidals: Correlated Deviations from the Baryonic Tully-Fisher Relation
• Infall Times for Milky Way Satellites From Their Present-Day Kinematics
• The Distribution of Alpha Elements in Ultra-Faint Dwarf Galaxies
• Tidal Signatures in the Faintest Milky Way Satellites: The Detailed Properties of Leo V, Pisces II and Canes Venatici II
• The structural properties and star formation history of Leo T from deep LBT photometry
• The Star Formation History and Extended Structure of the Hercules Milky Way Satellite
• Delving Deeper into the Tumultuous Lives of Galactic Dwarfs: Modeling Star Formation Histories
• The satellites of the Milky Way - Insights from semi-analytic modelling in a LambdaCDM cosmology
• The Stellar Populations and Structural Properties of Ultra Faint Dwarf Galaxies, Canes Venatici I, Bootes I, Canes Venatici II, and Leo IV
• Variable Stars in the Newly Discovered Milky Way Dwarf Spheroidal Satellite Canes Venatici I
• In Pursuit of the Least Luminous Galaxies
• Elemental Abundances in M31: The Kinematics and Chemical Evolution of Dwarf Spheroidal Satellite Galaxies
• Tidal disruption of globular clusters in dwarf galaxies with triaxial dark matter haloes
• Abundance ratios of red giants in low mass ultra faint dwarf spheroidal galaxies
• Numerical Color-Magnitude Diagram Analysis of SDSS Data and Application to the New Milky Way satellites
• The enigmatic pair of dwarf galaxies Leo IV and Leo V: coincidence or common origin?
• A Deeper Look at Leo IV: Star Formation History and Extended Structure
• Origin of the CEMP-no Group Morphology in the Milky Way
• A Megacam Survey of Outer Halo Satellites. II. Blue Stragglers in the Lowest Stellar Density Systems
• Identification of a Group III CEMP-no Star in the Dwarf Spheroidal Galaxy Canes Venatici I
• The scatter about the "Universal" dwarf spheroidal mass profile: A kinematic study of the M31 satellites, And V and And VI
• The First Galaxies and the Likely Discovery of their Fossils in the Local Group
• Searching for correlations in GAIA DR2 unbound star trajectories
• The Blue Straggler Population in Dwarf Galaxies
• Kinematic sub-populations in dwarf spheroidal galaxies
• Modelling the Canes Venatici I dwarf spheroidal galaxy
• A detailed star formation history of the distant Milky Way satellite Canes Venatici I: An old dwarf spheroidal forming most of its stars after reionisation