XMM-Newton imaging of V1818 Orionis: a young stellar group on the eastern edge of the κ Ori ring ^⋆

¹ INAF–Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
e-mail: pilli@astropa.inaf.it
² Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge (MA), 02138, USA
³ Ritter Astrophysical Research Center, Dept. of Physics and Astronomy, University of Toledo, Toledo, OH, USA

Received: 2 June 2017
Accepted: 13 November 2017

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 (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.