We present stellar metallicity measurements of more than 600 late-type stars in the central 10 pc of the Galactic centre .
Together with our previously published KMOS data , this data set allows us to investigate , for the first time , spatial variations of the nuclear star cluster ’ s metallicity distribution .
Using the integral-field spectrograph KMOS ( VLT ) we observed almost half of the area enclosed by the nuclear star cluster ’ s effective radius .
We extract spectra at medium spectral resolution , and apply full spectral fitting utilising the PHOENIX library of synthetic stellar spectra .
The stellar metallicities range from [ M/H ] =–1.25 dex to [ M/H ] > +0.3 dex , with most of the stars having super-solar metallicity .
We are able to measure an anisotropy of the stellar metallicity distribution .
In the Galactic North , the portion of sub-solar metallicity stars with [ M/H ] < 0.0 dex is more than twice as high as in the Galactic South .
One possible explanation for different fractions of sub-solar metallicity stars in different parts of the cluster is a recent merger event .
We propose to test this hypothesis with high-resolution spectroscopy , and by combining the metallicity information with kinematic data .