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analyses of the faint carina dsph have revealed that it contains a variety of stellar populations ( e.g. ,  [ 4 ] ) , exhibiting prominent old ( @xmath111gyr ) and intermediate - age ( 56 and 3gyr ) populations .
this implies that carina must have undergone several star forming ( sf ) episodes with at least three significant pulses . despite this wide spread in ages ,
its colour - magnitude diagram features a remarkably narrow rgb .
the reason for that can be an age counteracting spread in metallicities , where metal rich , young stars have colours comparable to the older , more metal poor ones .
such a possible age - metallicity degeneracy can be overcome if accurate and independent [ fe / h ] measurements are obtained so that the remaining parameter of age can be estimated from isochrones .
moreover , the overall shape and spatial variations of the metallicity distribution function ( mdf ) itself contain valuable implications for analysing carina s unusual sf history .
in the course of an eso large programme , we observed 1257 red giants covering five fields in carina out to the tidal radius .
our observations were performed during 23 nights with the multi - object spectrograph flames at the vlt in low - resolution mode , centered at the near infrared cat .
the data were reduced using the standard flames reduction pipline . since sky contamination from bright emission lines is strong in the cat region , we calculated an average sky - spectrum from 20 dedicated skyfibres , which then was carefully subtracted from the science spectra . typical signal - to - noise ( s / n ) ratios for our spectra lie between 25 and 150 pixel@xmath2 .
after rejection of foreground stars and stars with too low a s / n , 487 radial velocity members were analysed .
finally , metallicities were derived from the reduced equivalent width w@xmath3 ( [ 1],[5 ] ) .
the resulting mdf for our 487 red giants is shown in the top panel of fig .
1 . it is peaked at an average [ fe / h ] of @xmath4dex , which is in excellent agreement with the spectroscopic study of  [ 6 ] , who found a value of @xmath5dex .
we find a dispersion of @xmath6=0.25dex and as fig .
1 implies , the full spread of [ fe / h ] is at least one dex .
this suggests that the wide range in age is in fact counteracted by a wide spread in metallicity , which can explain carina s narrow rgb and confirms that a complex mixture of stellar populations as in carina does not necessarily contradict the rgb s narrowness .
the different stellar populations in carina have also different spatial distributions , where , the intermediate age red clump stars are clearly concentrated towards the center compared to the old hb ( see [ 1 ] )
. thus we plot in fig .  1 ( bottom panel ) the error - weighted mdfs for three different regions along the galaxy s axes .
while the curves for the central region and larger minor axis distances do not differ largely and also resemble those along the major axis , there is a shift of the mdf s peak towards the metal poor end by 0.2dex when concentrating on the outer , northwestern region ( lower axis distances ) .
1 also overplots a model curve from  [ 3 ] , showing the predicted mdf for carina .
this model uses a sf efficiency of 0.1gyr@xmath2 and a galactic wind efficiency at the lower end of wind rates in dsphs .
such a lower wind rate nicely explains the smooth decline of the observed mdf towards the metal rich end , as a higher wind rate would expel enriched gas more efficiently thus preventing the formation of this metal rich tail .
secondly , the low sf rate is able to explain the metal poor peak of the mdf in terms of a moderate enrichment history .
however , remaining caveats are the higher fraction of predicted extremely metal poor stars and the lower number of metal poor stars around [ fe / h]@xmath7 , which can be understood in the context of the low infall timescale of gas assumed in dsphs ( [ 3 ] ) . with our accurate [ fe / h ] measurements at hand we will in the next steps pursue the underlying age distribution and use the abundance ratios from our multi - object high - resolution spectroscopy to further unravel the mechanisms governing carina s evolutionary history .    .
the bottom plot shows spatially separated mdfs in three different regions of carina , measured along the major and minor axes.,title="fig:",width=453 ] .
the bottom plot shows spatially separated mdfs in three different regions of carina , measured along the major and minor axes.,title="fig:",width=453 ]      cole , a.a .
, et al . , mnras , 347 , 367 harbeck , d. , et .
2001 , aj , 122 , 3092 lanfrachi , g. , & matteucci , f. 2004 , mnras , 351 , 1338 monelli , m. , et al .
2003 , aj , 126 , 218 rutledge , g.a . ,
hesser , j.e . , stetson , p.b .
1997 , pasp , 109 , 907 smecker - hane , t.a .
, et al . 1999 , asp conf .
ser . , 192 , 159
we present metallicities for 487 red giants in the carina dwarf spheroidal ( dsph ) galaxy that were obtained from flames low - resolution ca triplet ( cat ) spectroscopy . 
 we find a mean [ fe / h ] of @xmath0dex with an intrinsic dispersion of 0.25dex , whereas the full spread in metallicities is at least one dex . 
 the analysis of the radial distribution of metallicities reveals that an excess of metal poor stars resides in a region of larger axis distances . 
 these results can constrain evolutionary models and are discussed in the context of chemical evolution in the carina dsph .