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We present radial velocities and [Fe/H] abundances for 340 stars in theFornax dwarf spheroidal from R~16,000 spectra. The targets have been obtainedin the outer parts of the galaxy, a region which has been poorly studiedbefore. Our sample shows a wide range in [Fe/H], between -0.5 and -3.0 dex, inwhich we detect three subgroups. Removal of stars belonging to the mostmetal-rich population produces a truncated metallicity distribution functionthat is identical to Sculptor, indicating that these systems have shared asimilar early evolution, only that Fornax experienced a late, intense period ofstar formation (SF). The derived age-metallicity relation shows a fast increasein [Fe/H] at early ages, after which the enrichment flattens significantly forstars younger than ~8 Gyr. Additionally, the data indicate a strong populationof stars around 4 Gyr, followed by a second rapid enrichment in [Fe/H]. Aleaky-box chemical enrichment model generally matches the observed relation butdoes not predict a significant population of young stars nor the strongenrichment at late times. The young population in Fornax may thereforeoriginate from an externally triggered SF event. Our dynamical analysis revealsan increasing velocity dispersion with decreasing [Fe/H] from sigma_sys 7.5km/s to >14 km/s, indicating an outside-in star formation history in a darkmatter dominated halo. The large velocity dispersion at low metallicities ispossibly the result of a non-Gaussian velocity distribution amongst stars olderthan ~8 Gyr. Our sample also includes members from the Fornax GCs H2 and H5. Inagreement with past studies we find [Fe/H]=-2.04+-0.04 and a mean radialvelocity RV=59.36+-0.31 km/s for H2 and [Fe/H]=-2.02+-0.11 and RV=59.39+-0.44km/s for H5. Overall, we find large complexity in the chemical and dynamicalproperties, with signatures that additionally vary with galactocentricdistance.

Insights from the Outskirts: Chemical and Dynamical Properties in the outer Parts of the Fornax Dwarf Spheroidal Galaxy