(Image: ESO/M. Fumagalli)

It’s the clash of the titans. As galaxy ESO 137-001 rams into its neighbours in the vast Norma cluster at several million kilometres per hour, it’s being stripped of most of the gas needed to make the next generation of stars.

The vibrant colours in this image represent moving gas, with blue indicating movement towards the Earth and red movement away. The original image, captured by the European Southern Observatory’s Very Large Telescope in Chile, captures a patch of glowing hydrogen gas surrounded by a sea of white and bluish stars..

Images in natural light of the galaxy changing colour as it quickly loses most of its fuel could help catch the moment when the switch happens, revealing more about the process.


“It is one of the major tasks of modern astronomy,” says Michele Fumagalli of Durham University in the UK, who led the research.

Solving the mystery could explain why star formation switches off in galaxy clusters.

Fumagalli and his team found that gas stripped from ESO 137-001 continues to turn in the same direction as its mother galaxy, even after being swept out into space. The rotation of stars in the galaxy also remains unchanged. This shows that the galaxy is being blown apart by pressure exerted by gas in the Norma cluster, rather than by gravity, which would disrupt the rotation.

See more stunning images from the telescopes of the European Southern Observatory in our gallery “Deep space drama: Top 10 views of the southern skies“.

Journal reference: Monthly Notices of the Royal Astronomical Society, DOI: 10.1093/mnras/stu2092