摘要：We present the results of a 40 ks XMM-Newton observation centered on the variable star V1818 Ori. Using a combination of the XMM-Newton and AllWISE catalog data, we identify a group of about 31 young stellar objects (YSOs) around V1818 Ori. This group is coincident with the eastern edge of the dust ring surrounding κ Ori. Previously, we concluded that the YSOs on the western side of ring were formed in an episode of star formation that started 3–5 Myr ago and are at a distance similar to that of κ Ori (250−280 pc) and in the foreground to the Orion A cloud. Here we use the XMM-Newton observation to calculate X-ray fluxes and luminosities of the young stars around V1818 Ori. We find that their X-ray luminosity function (XLF), calculated for a distance of ~270 pc, matches the XLF of the YSOs west of κ Ori. We rule out that this group of young stars is associated with Mon R2 as assumed in the literature; they are instead part of the same stellar population of the κ Ori ring.
