In the primary (NE) galaxy of NGC 6090, two distorted spiral arms are seen, both of which are delineated by a number of bright clusters. The companion, 6" (3.4 kpc) to the SW could almost be an extension of one of the primary's spiral arms; however, the bright 2.2 µm point source at the one end of the secondary together with a radio continuum source argue for this being a less massive galaxy which is merging with the NE galaxy. The 2.2 µm extinction-corrected contour map strongly favors this interpretation since the SW galaxy clearly appears very substantial and has only a low level bridge to the spiral pattern of the NE galaxy. The area between the two galaxies contains a massive concentration of ISM as evidenced by the very red colors of the clusters on the SW edge of the primary galaxy and the fact that the mm-wave CO(1-0) emission peaks in this overlap region (Bryant & Scoville 1999). The morphology of NGC 6090 suggests an extended starburst triggered by the galaxy-galaxy interaction. The large number of luminous clusters seen along the side of the NE galaxy closest to the secondary galaxy suggests that the starbursts are triggered hydrodynamically (eg. cloud-cloud collisions or shocks from a high pressure, intercloud medium) rather than by large-scale gravitational force gradients. (Tidal effects should be equal on the near and far sides contrary to the observed asymmetry.) Dinshaw et al. (1999) present a more detailed description of these data, and conclude, in part, that the radio emission from NGC 6090SW is not coincident with the brightest near-infrared ``knot'', and that this knot may actually be a forground star.

Shaded contour plots of the extinction corrected 2.2 µm emission are shown together with the 1.1 µm (upper left) observed emission. In both panels, the contours and shading are logarithmic with the contours spaced by factors 2^1/2. (The level values are the same as for the figure above). The arcsec displacements in RA and DEC, given along the borders are measured from the 2.2 µm in all frames. At the upper left, a length bar is drawn. For the ratio image, both the 2.2 and 1.1 µm images were smoothed with the same adaptive smoothing and then smoothed with a Gaussian FWHM = 0.2" in calculating the 2.2 µm opacity from Eq. 3 (see text). In cases where a strong point-source or variable background contaminated the 2.2 µm image, the extinction corrected image was derived for 1.6 µm. For the galaxies with strong point-sources, the PSF was fit to the source and then subtracted and replaced by a Gaussian with the proper integrated flux (see text - NGC 7469, IRAS 08572+3915, IRAS 05189-2524, PKS 1345+12, IRAS 07598+6508, Mrk 1014 and 3C48).