EVIDENCE FOR A MERGER IN THE PECULIAR VIRGO CLUSTER SA GALAXY NGC-4424

We present R-band and H alpha images and H alpha long-slit spectroscop y of the peculiar Virgo cluster Sa galaxy NGC 4424. The broadband R im age reveals banana-shaped isophotes, shell-like features, and other co mplex structure generally associated with mergers and significant accr etion events. The only H alpha emission arises from a few bright H II complexes located within 500 pc of the nucleus and inside the bulge-do minated region. Although the main stellar body of NGC 4424 is highly e longated in projection, and the outer part of the galaxy has a disk-li ke exponential light profile, gas velocities are remarkably low in the central kpc, indicating strong non-circular motions or complex geomet ry for the inner gas. The peculiar properties are consistent with an i ntermediate mass ratio (0.1-0.5) merger making NGC 4424 one of the bes t cases among spiral galaxies in the nearby Virgo cluster for a signif icant and recent merger. The degree of morphological peculiarities sug gest that the merger is recent, and we propose that the galaxy will be come a small-bulge SO within similar to 1 Gyf. We discuss the possibil ity that the banana-shaped stellar distribution is the result of a mer ger-induced bending instability. (C) 1996 American Astronomical Societ y.