Near-infrared observations of the Fornax dwarf galaxy. I. The red giant branch

Abstract

We present a study of the evolved stellar populations in the dwarf spheroidal galaxy Fornax based on JHK imaging photometry. The observations cover an 18.5x18.5 arcmin central area with a mosaic of NTT/SOFI images. Our data sample all the red giant branch for the whole area. Deeeper observations reaching the red clump of helium-burning stars have also been obtained for a 4.5 x 4.5 arcmin region. Near-infrared photometry led to measurements of the distance to Fornax based on the K-band location of the RGB tip and the red clump. Once corrected for the mean age of the stellar populations in the galaxy, the derived distance modulus is 20.74 corresponding to a distance of 141 Kpc, in good agreement with estimates from optical data. By taking age effects into account, we have derived a distribution function of global metallicity [M/H] from optical-infrared colors of individual stars. Our photometric Metallicity Distribution Function covers the range -2.0<[M/H]<-0.6, with a main peak at [M/H]~-0.9 and a long tail of metal-poor stars, and less metal-rich stars than derived by recent spectroscopy. If metallicities from CaII triplet lines are correct, this result confirms a scenario of enhanced metal enrichment in the last 1-4 Gyr.

arXiv commentaccepted for publication in Astronomy and Astrophysics

References in corpus (28)

• Dwarf Galaxies of the Local Group
• A large stellar evolution database for population synthesis studies. I. Scaled solar models and isochrones
• Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets
• Color Transformations for the 2MASS Second Incremental Data Release
• Abundances for Globular Cluster Giants: I. Homogeneous Metallicities for 24 Clusters
• VLT/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies: I. Nucleosynthesis and Abundance Ratios
• Age and Metallicity Distribution of the Galactic Bulge from Extensive Optical and Near-IR Stellar Photometry
• The DART imaging and CaT survey of the Fornax Dwarf Spheroidal Galaxy
• A Comparison of Elemental Abundance Ratios in Globular Clusters, Field Stars, and Dwarf Spheroidal Galaxies
• VLT/UVES Abundances in Four Nearby Dwarf Spheroidal Galaxies: II. Implications for Understanding Galaxy Evolution
• K-Band Calibration of the Red Clump Luminosity
• Population effects on the red giant clump absolute magnitude: The K-band
• Tip of the Red Giant Branch Distances. I. Optimization of a Maximum Likelihood Algorithm
• WIYN Open Cluster Study. X. The K-Band Magnitude of the Red Clump as a Distance Indicator
• Using the Ca II Triplet to Trace Abundance Variations in Individual Red Giant Branch stars in Three Nearby Galaxies
• The Red Giant Branch in the Near-Infrared Colour-Magnitude Diagrams. I: The calibration of photometric indices
• An abundance analysis for four Red Horizontal Branch Stars in the extremely metal rich globular cluster NGC 6528
• The Red Giant Branch in Near-Infrared Colour-Magnitude Diagrams. II: The luminosity of the Bump and the Tip
• The Chemical Enrichment History of the Fornax Dwarf Spheroidal Galaxy from the Infrared Calcium Triplet
• Variable Stars in the Fornax Dwarf Galaxy
• The Age Dependent Luminosities of the Red Giant Branch Bump, Asymptotic Giant Branch Bump, and Horizontal Branch Red Clump
• Tip of the Red Giant Branch distances to galaxies with composite stellar populations
• Observational discovery of the AGB-bump in densely populated color-magnitude diagrams of galaxies and star clusters
• V, J, H and K Imaging of the Metal Rich Globular Cluster NGC 6528
• The Sagittarius dwarf irregular galaxy: metallicity and stellar populations
• Neutral Hydrogen Clouds near Early-Type Dwarf Galaxies of the Local Group
• Improved Searches for HI in Three Dwarf Spheroidal Galaxies
• Stellar Populations in the Local Group of Galaxies

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