Astronomers from the National Centre for Radio Astrophysics (NCRA), Pune have discovered a galaxy that lies within a ring of hydrogen. The galaxy, AGC 203001 located about 260 million light-years away, was discovered using the Giant Metrewave Radio Telescope (GMRT).
The off-centered hydrogen ring that shrouds the galaxy is much bigger compared to the galaxy itself, with a diameter of 380,000 light-years, is four times the size of the Milky Way galaxy. Such ring galaxies are thought to have been the result of a collision between two galaxies that causes the gas and stars to expand in the form of a ring. The scientists explained their findings in a paper published in the Monthly Notices of the Royal Astronomical Society.
Astronomers explained that such ringed structures around galaxies are very rare as only one other such structure has been observed – the Leo Ring. No stars were observed in this particular ring which left scientists puzzled, as other such gas rings found have contained stars. While it is still unclear how these off-centered gaseous rings form, the formation of starless rings of hydrogen is also a mystery. As in the case of formation by collision, researchers explain, in such a scenario the impact also leads to large amounts of star formation in the ring that is not observed in the ring.”
The team, in their future studies, will conduct large surveys to map the rings of neutral hydrogen around similar galaxies to achieve insights into the rare phenomena.
Image Credit: O. Bait (NCRA-TIFR/GMRT), Duc (ObAS/CFHT)