We present XMM-Newton , Chandra and VLA observations of the USGC S152 group and its central elliptical NGC 3411 .
Imaging of the group X-ray halo suggests it is relaxed with little apparent structure .
We investigate the temperature and metal abundance structure of the group halo , and find that while the abundance distribution is fairly typical , the temperature profile is highly unusual , showing a hot inner core surrounded by a cool shell of gas with a radius of \sim 20-40 kpc , at the center of the larger group halo .
Spectral mapping confirms an irregular ring of gas \sim 0.15 keV cooler than its surroundings .
We estimate the total mass , entropy and cooling time profiles within \sim 200 kpc , and find that the cool shell contains \sim 9 \times 10 ^ { 9 } M _ { \odot } of gas .
VLA observations at 1.4 , 5 and 8 GHz reveal a relatively weak nuclear radio source , with a core radio luminosity L _ { R } =2.7 \times 10 ^ { 38 } \mbox { ~ { } erg } \mbox { ~ { } s } ^ { -1 } , and a diffuse component extended on scales of a few arcseconds ( or more ) .
A lack of evidence for activity at optical or X-ray wavelengths supports the conclusion that the central black hole is currently in a quiescent state .
We discuss possible mechanisms for the formation of temperature features observed in the halo , including a previous period of AGN activity , and settling of material stripped from the halo of one of the other group member galaxies .