X-rays from V838 Mon: a New Magnetic Dynamo, or Ejecta-Companion Interactions?

Our discovery with XMM in 2008 of a composite X-ray source that is spatially coincident with V838 Mon has placed unique new constraints on models put forward to explain its 2002 outburst. The properties of the V838 Mon X-ray source are consistent with a stellar merger scenario for the outburst. Alternatively, the X-ray source(s) could be indicative of interactions between ejecta from V838 Mon and its early-type conpanion. Given the complete disappearance of the companion star into V838 Mon's ejecta shortly after our XMM detection, the new 100 ks observation proposed here will distinguish between these two X-ray source origins.