Pan: A dynamic duo … or trio?

This captivating image captures the interaction between two galaxies, identified as Arp-Madore 2339-661 from the catalogue of peculiar galaxies. However, the intrigue deepens as it turns out that there are three galaxies engaged in this cosmic dance, not just two.

The prominent pair consists of NGC 7733 (smaller, lower right) and NGC 7734 (larger, upper left). The third participant, currently known as NGC 7733N, reveals itself in this image. If you examine the upper arm of NGC 7733 closely, you'll notice a distinctive knot-like structure, radiating a different color than the arm and partially obscured by dark dust. While it may appear integral to NGC 7733, velocity analysis indicates a significant additional redshift, strongly suggesting that it is a distinct entity, not part of NGC 7733. This highlights one of the challenges faced by observational astronomers — distinguishing whether an astronomical object is a singular entity or one positioned in front of another from Earth's perspective.

Situated approximately 500 million light-years away in the constellation Tucana, these three galaxies are in close proximity and are gravitationally interacting, potentially forming a 'merging group.' This term suggests that they are on a trajectory to eventually merge into a singular cosmic entity.