We present results from a short Chandra /ACIS-S observation of NGC 7618 , the dominant central galaxy of a nearby ( z =0.017309 , d=74.1 Mpc ) group .
We detect a sharp surface brightness discontinuity 14.4 kpc N of the nucleus subtending an angle of 130 ^ { \circ } with an X-ray tail extending \sim 70 kpc in the opposite direction .
The temperature of the gas inside and outside the discontinuity is 0.79 \pm 0.03 and 0.81 \pm 0.07 keV , respectively .
There is marginal evidence for a discontinuous change in the elemental abundance ( Z _ { inner } =0.65 \pm 0.25 , Z _ { outer } =0.17 \pm 0.21 at 90 % confidence ) , suggesting that this may be an ‘ abundance ’ front .
Fitting a two-temperature model to the ASCA/GIS spectrum of the NGC 7618/UGC 12491 pair shows the presence of a second , much hotter ( T = \sim 2.3 keV ) component .
We consider several scenarios for the origin of the edge and the tail including a radio lobe/IGM interaction , non-hydrostatic ‘ sloshing ’ , equal-mass merger and collision , and ram-pressure stripping .
In the last case , we consider the possibility that NGC 7618 is falling into UGC 12491 , or that both groups are falling into a gas poor cluster potential .
There are significant problems with the first two models , however , and we conclude that the discontinuity and tail are most likely the result of ram pressure stripping of the NGC 7618 group as it falls into a larger dark matter potential .