Cosmic "ribbon" wrapped galaxy discovered

  There are many unusual galaxies in the universe. But some are more so than others. Some, just by looking at them, leave you speechless and open up a world of questions, even more so than ordinary galaxies. A few days ago, astronomers revealed one of these very special galaxies in a study. What makes NGC 4632 - that's the name of the cosmic giant 56 million light-years away from us - different from the average one is easy to say, just take a look at the image: it is surrounded by a huge ring of gas that is perpendicular to the main galactic disk.

Composite image of NGC 4632 obtained by combining radio data from ASKAP with optical and infrared data from the Subaru Telescope in Hawaii. Credits: J. English (U.Manitoba), with assistance from T. Jarrett (UCT) and the WALLABY team: ATNF/ASKAP: Suburu/Hyper Suprime Camera

What is this all about? 

First, let's try to understand what this mysterious ring surrounding the galaxy is. As always, science is a work in progress, and you don't have all the answers when you first make a discovery. However, the astronomers who authored the study have begun to speculate, in part because this is not the first polar ring found around a galaxy, although they are quite rare (1 to 3 percent of galaxies would have them). One possible explanation is that the stellar rings, which appear mixed in with clouds of gas, are shredded material from passing galaxies. Another possibility is that hydrogen gas flows along the filaments of the cosmic web and grows into a ring around some galaxies, possibly forming stars in the process.

How was the ring detected?

To detect this polar ring, astronomers used the ASKAP radio telescope, which is owned and operated by CSIRO, Australia's national science agency. In fact, this particular structure can only be seen in radio waves. NGC 4632 is one of two polar ring galaxies the researchers identified among the 600 galaxies mapped in the first survey, called WALLABY. 

In the future, polar ring galaxies may also be used to deepen our understanding of the universe, with potential applications in the search for dark matter. Polar rings can be used to probe the shape of the host galaxy's dark matter, which could lead to new clues about the mysterious properties of this elusive "substance".