Astronomers spot a mysterious galaxy wrapped in a cosmic “ribbon”
What astronomers thought was a pretty normal spiral galaxy not far from the Milky Way has revealed a cosmic gift.
By CSIRO
Dr Jayanne English, an expert in astronomy image-making at the University of Manitoba, combined data obtained from ASKAP with optical and infrared data from the Subaru telescope in Hawaii to make the dramatic composite image of NGC 4632. Credit: J. English (U.Manitoba), with support of T. Jarrett (UCT) and the WALLABY team: ATNF/ASKAP:Suburu/Hyper Suprime Camera
International astronomers using a telescope owned and operated by CSIRO, Australia’s national science agency, have revealed a galaxy wrapped in a cosmic ‘ribbon’.
The research, led by Dr Nathan Deg and Dr Kristine Spekkens from Queen’s University Canada and co-authored by CSIRO’s Professor Bärbel Koribalski, presents a stunning image of a galaxy called NGC 4632 that is 56 million light years from Earth in Monthly Notices of the Royal Astronomical Society.
Polar ring galaxies might be more common than previously thought.
It’s been identified as a potential polar ring galaxy, which are some of the most spectacular types of galaxies in the Universe, and among the most mysterious.
Detected using CSIRO’s ASKAP radio telescope on Wajarri Yamaji Country in Western Australia, the galaxy features a ring of gas that can only be seen at radio wavelengths. The ring is orbiting the galaxy at right angles to its spiral disk, like a parcel wrapped in a ribbon of cosmic gas, dust and stars.
“The findings suggest that one to three per cent of nearby galaxies may have gaseous polar rings, which is much higher than suggested by optical telescopes. Polar ring galaxies might be more common than previously thought,” Dr Deg said.
CSIRO's ASKAP radio telescope under the Milky Way on Wajarri Yamaji Country. Credit: CSIRO/A. Chern
“While this is not the first time astronomers have observed polar ring galaxies, NGC 4632 is the first observed with ASKAP and there may be many more to come."
Professor Koribalski said the WALLABY survey aims to observe the whole southern sky using ASKAP to detect and visualise the gas distribution in hundreds of thousands of galaxies.
“NGC 4632 is one of two polar ring galaxies we’ve identified from 600 galaxies that were mapped in our first small WALLABY survey," Professor Koribalski said.
They expect to reveal more than 200,000 hydrogen-rich galaxies.
“Using ASKAP over coming years we expect to reveal more than 200,000 hydrogen-rich galaxies, among them many more unusual galaxies like these ones with polar rings."
Why polar rings exist is still a puzzle to astronomers. One possible explanation is that their stellar rings, which appear blended with gas clouds, are shredded material from a passing galaxy.
Another possibility is that hydrogen gas flows along the filaments of the cosmic web and accretes into a ring around a galaxy, possibly forming stars during this process.
In the future, polar ring galaxies can also be used to deepen our understanding of the universe, with potential applications in dark matter research. It is possible to use polar rings to probe the shape of dark matter of the host galaxy, which could lead to new clues about the mysterious properties of the elusive substance.
Provided by CSIRO
Reference: N. Deg, R. Palleske, K. Spekkens, J. Wang, T. Jarrett, J. English, X Lin, J. Yeung, J. R. Mould, B. Catinella, H. Dénes, A. Elagali, B -Q For, P. Kamphuis, B. S. Koribalski, K. Lee-Waddell, C. Murugeshan, S. Oh, J. Rhee, P. Serra, T. Westmeier, O. I. Wong, K. Bekki, A. Bosma, C. Carignan, B. W. Holwerda, N. Yu. WALLABY pilot survey: the potential polar ring galaxies NGC 4632 and NGC 6156. Monthly Notices of the Royal Astronomical Society (2023). DOI: https://doi.org/10.1093/mnras/stad2312
