Interacting Binary Galaxies. VI. The Fast Encounter of NGC 2672 and NGC 2673 (Karachentsev 175, ARP 167)

We have studied the isolated pair of interacting ellipticals NGC 2672/2673 (Arp 167; Karachentsev 175), whose line-of-sight relative velocity is ~520 km s^-1^. Rotation and velocity dispersion profiles have been measured along the line connecting the galaxy centers, and broad-band CCD images have been obtained in three colors. The smaller of the two galaxies (NGC 2673; K175b; E0p) has two tidal "plumes" in its light distribution, while the larger galaxy (NGC 2672; K175a; E2) is only weakly disturbed. Velocity dispersion is roughly constant with radius in NGC 2672, but appears to increase with radius in the small galaxy, indicative of strong tidal heating. Weak counter rotation (i.e., opposite the orbital motion) is seen in NGC 2672 such that V_rot_/σ = 0.16. The secondary galaxy (NGC 2673) has a nearly flat rotation profile along the slit, with some indication of a U-shaped component, providing evidence for the action of tidal friction. Numerical simulations have been run in order to elucidate the dynamical properties of this galactic encounter. Our models require a fast hyperbolic passage with very small pericenter separation, and they require a rapidly rotating secondary galaxy in order to produce the observed plumes on K175b. One of these plumes is straight, which is qualitatively different in appearance and origin from the usual curved tidal tails seen in colliding galaxies. Our adopted solution for K175 provides a complete dynamical description of the pair, including the spatial orientation of the orbit and its dynamical mass. The derived M/L_B_<=7 M_0_/L^B^_0_ for the pair does not require a significant nonluminous contribution to the system mass.