NICMOS observations of interaction-triggered star formation in the luminous infrared galaxy NGC 6090

High-resolution 1.1, 1.6, and 2.2 μm imaging of the luminous infrared galaxy NGC 6090 obtained with NICMOS on the Hubble Space Telescope is presented. These new observations are centered on the two nuclei of the merger and reveal the spiral structure of the eastern galaxy and the amorphous nature of the western galaxy. The nuclear separation of 3.2 kpc (H₀ = 75 km s^-1 Mpc^-1) indicates that NGC 6090 is at an intermediate stage of merging. Bright knots/clusters are also visible in the region overlapping the merging galaxies ; four of these knots appear bluer than the underlying galaxies and have colors consistent with young (<10⁷ yr) star clusters. The spatial coincidence of the knots with the molecular gas in NGC 6090 indicates that much of the present star formation is occurring outside the nuclear region of merging galaxies, consistent with recent studies of other double nucleus luminous infrared galaxies.