Searching for long-term spectral evolution in the Magnificent Seven

RX J0720.43125 is unique among the Magnificent Seven (M7) isolated neutronstars, showing longterm variations in its Xray spectrum over more than 10years. If the M7 stars are indeed descendants of magnetars, then a decayingmagnetic field leads to decreasing magneticallydriven glitch activity and it isconceivable that also other members of the group exhibit a similar behaviour. Wepropose snapshot XMMNewton observations of the four M7 stars RBS1223, RBS1774,RX J0806.44123 and RX J0420.05022 to look for longterm spectral changes. TheEPICpn observations will achieve an accuracy of better than 2 eV in thetemperature determination, sufficient for comparison with archival observationsand to identify an event as observed from RX J0720.43125. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]