Hubble Hunts an Unusual Galaxy

The galaxy merger Arp-Madore 417-391 steals the spotlight in this image from the NASA/ESA Hubble Space Telescope. The Arp-Madore catalogue is a collection of particularly peculiar galaxies spread throughout the southern sky, and includes a collection of subtly interacting galaxies as well as more spectacular colliding galaxies . Arp-Madore 417-391, which lies around 670 million light-years away in the constellation Eridanus in the southern celestial hemisphere, is one such galactic collision. The two galaxies have been distorted by gravity and twisted into a colossal ring, leaving the cores of the two galaxies nestled side by side.

Hubble used its Advanced Camera for Surveys (ACS) to capture this scene — the instrument is optimised to hunt for galaxies and galaxy clusters in the ancient Universe. Hubble’s ACS has been contributing to scientific discovery for 20 years , and throughout its lifetime it has been involved in everything from mapping the distribution of dark matter to studying the evolution of galaxy clusters.

This image comes from a selection of Hubble observations designed to create a list of intriguing targets for follow-up observations with the NASA/ESA/CSA James Webb Space Telescope , as well as other ground-based telescopes. Astronomers chose a list of previously unobserved galaxies for Hubble to inspect between other scheduled observations. Over time, this lets astronomers build up a menagerie of interesting galaxies while using Hubble’s limited observing time as fully as possible.

Image description

Image description: Two galaxies right of centre form a ring shape. The ring is narrow and blue, and the cores of the two galaxies form a bulge on the ring’s side. A bright, orange star lies above the ring. Two smaller spiral galaxies appear left of centre, as well as a few stars. The background is black and speckled with very small stars and galaxies.