A new adventure of the musketeer PSR B1055-52

The nearby, middleaged neutron star PSR B105552, one of the socalled ThreeMusketeers, has been observed once by XMMNewton in 2000 resulting in a detailedphaseresolved spectral analysis. Chandra observations in 2012 show spectralchanges and an apparent >30% flux decrease with respect to the 2000 XMMNewtonobservation. These changes are too large to be due to crosscalibrationproblems. We propose new XMMNewton observations to probe the apparent spectralchanges. Using a better suited instrument mode than the 2000 observations, wewill also be able to measure more accurately the magnetospheric spectralcomponent and relate it to the radio and gammaray pulse profiles. Furthermore,we will search for phasedependent absorption features in the new epoch data. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]