XMM-Newton imaging of V1818 Ori: a young stellar group on the eastern edge of the Kappa Ori ring

TL;DR

This study uses XMM-Newton X-ray observations combined with infrared data to identify and analyze a young stellar group on the eastern edge of the Kappa Ori ring, revealing its properties and relation to the star formation history of the region.

Contribution

It provides the first X-ray characterization of the young stellar group around V1818 Ori and clarifies its association with the Kappa Ori ring rather than Mon R2.

Findings

The young stellar group around V1818 Ori is part of the Kappa Ori ring stellar population.

Their X-ray luminosity function matches that of the western group, indicating similar ages and distances.

The group is not associated with Mon R2, contrary to previous assumptions.

Abstract

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.