XMM-Newton imaging of V1818 Ori: a young stellar group on the eastern
  edge of the Kappa Ori ring
  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 around
V1818 Ori. This group is coincident with the eastern edge of the dust ring
surrounding Kappa Ori. Previously, we concluded that the young stellar objects
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 kappa 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 Kappa
Ori. We rule out that this group of young stars is associated to Mon R2 as
assumed in the literature, but rather they are part of the same Kappa Ori's
ring stellar population.
