Cooling of the super-heated neutron star in MAXI J0556-332

We propose to continue our highly successful coverage of the cooling neutronstar in MAXI J0556332, which was strongly heated during a near/superEddingtonoutburst in 2011/12 and again during a smaller outburst in 2016. Our quiescentobservations, which revealed an extraordinarily hot and rapidly cooling neutronstar, have provided unique insights into neutronstar structure and inparticular into the nature of heat sources in the shallow outer crust. Recentobservations suggest that the ongoing cooling trend is now dominated by heatinduced during the first outburst in deeper crustal layers. We request a 106 ksXMMNewton observation to investigate if the remarkable properties of the outercrust extend to deeper layers where matter reaches nuclear density. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]