In earlier work , we showed for the first time that the resolved stellar disk of NGC 300 is very extended with no evidence for truncation , a phenomenon that has since been observed in other disk galaxies .
We revisit the outer disk of NGC 300 in order to determine the metallicity of the faint stellar population .
With the GMOS camera at Gemini South , we reach 50 \% completeness at ( g ^ { \prime } , i ^ { \prime } ) = ( 26.8 - 27.4 , 26.1 - 27.0 ) in photometric conditions and 0.7 ” seeing .
At these faint depths , careful consideration must be given to the background galaxy population .
The mean colors of the outer disk stars fall within the spread of colors for the background galaxies , but the stellar density dominates the background galaxies by \sim 2 : 1 .
The predominantly old stellar population in the outer disk exhibits a negative abundance gradient – as expected from models of galaxy evolution – out to about 10 kpc where the abundance trend changes sign .
We present two scenarios to explain the flattening , or upturn , in the metallicity gradient of NGC 300 and discuss the implication this has for the broader picture of galaxy formation .