X-ray emission from young Brown Dwarfs in the sigma Orionis association

We propose for XMMNewton observations of very lowmass objects in the youngstellar association around the multiple star sigma Orionis. Our scientific goalis to study magnetic activity of young objects from the hydrogen burning masslimit down to the deuterium burning limit. The sig Ori association contains anumber of objects with planetary masses and Brown Dwarfs (BDs); some of thelatter ones were shown to be Xray sources in ROSAT pointings. We plan amultiwavelength study including Xray and optical observations as magneticactivity is manifested in a large range of the spectrum. These observationscould lead to the first Xray detection of objects close to the planetary masslimit and help to discriminate between BDs and planets in this region. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]