XMM-Newton observations of the young open cluster around λ Orionis

Aims. We studied the X-ray properties of the young (similar to 1-8 Myr) open cluster around the hot (O8 III) star lambda Ori and compared them with those of the similarly-aged sigma Ori cluster to investigate possible effects of the different ambient environment. Methods. We analysed an XMM-Newton observation of the cluster using EPIC imaging and low-resolution spectral data. We studied the variability of detected sources, and performed a spectral analysis of the brightest sources in the field using multi-temperature models. Results. We detected 167 X-ray sources, of which 58 are identified with known cluster members and candidates, from massive stars down to low-mass stars with spectral types similar to M5.5. Another 23 sources were identified with new possible photometric candidates. Late-type stars have a median log L(X)/L(bol) similar to -3.3, close to the saturation limit. Variability was observed in similar to 35% of late-type members or candidates, including six flaring sources. The emission from the central hot star lambda Ori is dominated by plasma at 0.2-0.3 keV, with a weaker component at 0.7 keV, consistently with a wind origin. The coronae of late-type stars can be described by two plasma components with temperatures T(1) similar to 0.3-0.8 keV and T(2) similar to 0.8-3 keV, and subsolar abundances Z similar to 0.1-0.3 Z(circle dot), similar to what is found in other star-forming regions and associations. No significant difference was observed between stars with and without circumstellar discs, although the smallness of the sample of stars with discs and accretion does not allow us to draw definitive conclusions. Conclusions. The X-ray properties of lambda Ori late-type stars are comparable to those of the coeval sigma Ori cluster, suggesting that stellar activity in lambda Ori has not been significantly affected by the different ambient environment.