  Aims: We present a study of the Galactic supernova remnant SNR G15.9+0.2 with
archival XMM-Newton observations. Methods: EPIC data are used to investigate
the morphological and spectral properties of the remnant, searching in
particular for supernova ejecta and Fe K line emission. By comparing the SNR's
X-ray absorption column density with the atomic and molecular gas distribution
along the line of sight, we attempt to constrain the distance to the SNR.
Results: Prominent line features reveal the presence of ejecta. Abundance
ratios of Mg, Si, S, Ar, and Ca strongly suggest that the progenitor of SNR
G15.9+0.2 was a massive star with a main sequence mass likely in the range
20-25 $M_{\odot}$, strengthening the physical association with a candidate
central compact object detected with Chandra. Using EPIC's collective power, Fe
K line emission from SNR G15.9+0.2 is detected for the first time. We measure
the line properties and find evidence for spatial variations. We discuss how
the source fits within the sample of SNRs with detected Fe K emission and find
that it is the core-collapse SNR with the lowest Fe K centroid energy. We also
present some caveats regarding the use of Fe K line centroid energy as a typing
tool for SNRs. Only a lower limit of 5 kpc is placed on the distance to SNR
G15.9+0.2, constraining its age to $t_{SNR} \gtrsim 2$ kyr.
