The nearby group centered on its bright central galaxy NGC 1407 has been suggested to be an unusually dark system from previous kinematic studies .
It is also known for hosting a bright galaxy , NGC 1400 , with a large radial velocity ( 1200 km s ^ { -1 } ) with respect to the group center .
Previous ROSAT X-ray observations revealed an extended region of enhanced surface brightness just eastward of NGC 1400 .
We investigate the NGC 1407/1400 complex with XMM-Newton and Chandra observations .
We find that the temperature and metallicity of the enhanced region are different ( cooler and more metal rich ) than those of the surrounding group gas , but consistent with those of the ISM in NGC 1400 .
The relative velocity of NGC 1400 is large enough that much of its ISM could have been ram pressure stripped while plunging through the group atmosphere .
We conclude that the enhanced region is likely to be hot gas stripped from the ISM of NGC 1400 .
We constrain the motion of NGC 1400 using the the pressure jump at its associated stagnation front and the total mass profile of the NGC 1407 group .
We conclude that NGC 1400 is moving within \sim 30 ^ { \circ } of the line-of-sight with Mach number \mathcal { M } \lesssim 3 .
We do not detect any obvious shock features in this complex , perhaps due to the highly line-of-sight motion of NGC 1400 .
With an XMM-Newton pointing on the relatively relaxed eastern side of NGC 1407 , we derive a hydrostatic mass for this group of \sim 1 \times 10 ^ { 13 } M _ { \odot } within 100 kpc .
The total mass extrapolated to the virial radius ( 681 kpc ) is 3.8 \times 10 ^ { 13 } M _ { \odot } , which puts an upper limit of \sim 300 M _ { \odot } / L _ { B _ { \odot } } on the mass-to-light ratio of this group .
This suggests that the NGC 1407 group is not an unusually dark group .