Tidal Currents in the Peacock’s Domain
In the southern constellation of Pavo — Latin for peacock — spiral galaxies IC 4585 (top) and IC 4584 (bottom) engage in a slow gravitational dance, distorting one another through tidal forces that will likely lead to a future merger.
IC 4585, a barred spiral (SBc), displays clear signs of disruption: a broad tidal arm arcs upward from the disk, and a faint, diffuse bridge of material connects it to IC 4584, a face-on spiral classified as SA(rs)c. Though less disturbed, IC 4584 shows gentle warping in its outer arms, especially on the side facing its companion, revealing the subtle pull of tidal influence.
Bluish regions near the center of IC 4585 mark recent star formation, likely triggered by gravitational compression. The presence of a tidal bridge suggests the galaxies have already passed near one another and are now gravitationally bound. Over time, this interaction may culminate in their eventual merger.
The field is overlaid with a dense foreground of Milky Way stars, as Pavo lies deep in the southern galactic plane. This makes image processing particularly challenging, as faint tidal features must be preserved amid a crowded background of bright stellar intrusions.
Located about 160 million light-years away, IC 4585 stretches nearly 100,000 light-years, while IC 4584 spans about 70,000 light-years. Their apparent angular sizes are roughly 2.2 × 0.7 arcminutes and 1.6 × 1.2 arcminutes, respectively.
This image offers a glimpse into a slow cosmic interaction, where gravity is sculpting two spiral galaxies — and their future.
Imaged in LRGB on my Planewave CDK 1000 at Observatorio El Sauce, Chile.
Image acquisition and processing: Mike Selby