MULTIPLE HIGH-VELOCITY EMISSION-LINE SYSTEMS IN THE E-29(S PAIR CPG)

A detailed study of the mixed-morphology galaxy pair CPG 29 (Arp 119, VV 347) shows spectacular spectroscopic peculiarities in the southern (spiral) component (Mrk 984) including a spatially resolved region, ro ughly aligned along the minor axis of the galaxy, with multiple emissi on-line components redshifted by as much as 1300 km s(-1) with respect to the LINER nucleus. Strong [O I] lambda 6300 and [S II] lambda lamb da 6716, 6731 emission suggest shock ionization. The rest of the galax y's disk is spectroscopically undistinguished, with emission lines cha racteristic of disk H II regions and, in large part, ordered rotation. We discuss the following four possible explanations for the morpholog ical and spectroscopic peculiarities in the spiral: (1) a superwind sc enario, supported by the high FIR luminosity of the spiral and by emis sion-line activity similar to that observed in FIR-strong galaxies; (2 ) motion of the spiral through a hot, relatively dense intergalactic m edium, possibly associated with the elliptical, that could affect the star formation and create a brightened disk rim; (3) a faint companion in direct collision with the disk, at Delta upsilon(r) similar to 100 0 km s(-1), that would straightforwardly explain the existence of the different redshift systems; and (4) a pole-on collision by the ellipti cal, that could produce the disturbed morphology and other properties of the spiral. The elliptical/spiral pole-on collision explains the hi gh-velocity line-emitting regions as tidally stripped gas and accounts for the presence of gas ionized by moderate velocity shocks. The morp hology of Mrk 984 is consistent with a ring galaxy and numerical simul ations suggest that the elliptical can emerge unscathed from a relativ ely high velocity crossing.