Hubble captures strange triple galactic dance

2023-10-27 17:29:29

MADRID, 27 Oct. (EUROPA PRESS) –

This unique image of NASA/ESA Hubble Space Telescope captures the pair of interacting galaxies known as Arp-Madore 2339-661.

The Arp-Madore catalog is a collection of peculiar galaxies, and the particular peculiarity of this group could be stranger than it seems at first glance, since here there are three galaxies interactingnot just two.

The two clearly defined galaxies are NGC 7733 (smaller, lower right) and NGC 7734 (larger, upper left). The third galaxy is currently known as NGC 7733N. and is visible if you look closely at the upper arm of NGC 7733.

There you can see a knot-shaped structure, glowing a different color than the arm and obscured by dark dust. This could easily pass as part of NGC 7733, but analysis of the velocities (speed and direction) involved reveals that this knot has considerable additional redshift. This means that it is most likely its own entity and not part of NGC 7733.

This group of galaxies presents one of the many challenges facing observational astronomers: determining whether an astronomical object is really just one or several objects, one of which lies in front of it. Another seen from Earth’s perspective.

The three galaxies are located quite close to each other, about 500 million light years from Earth, in the Tucana constellation, and, as this image shows, they interact gravitationally with each other. In fact, some scientific literature refers to them as a “merging group,” meaning that they will ultimately become a single entity, NASA reports.