Odd radio circle

"ORCs" redirects here. For the singular form, see orc (disambiguation).

In astronomy, an odd radio circle (ORC) is a very large (over 50 times the diameter of our Milky Way ~ 3 million light years) unexplained astronomical object that, at radio wavelengths, is highly circular and brighter along its edges. As of October 2025, there have been 8 such objects (and possibly six more) observed. The observed ORCs are bright at radio wavelengths, but are not visible at visible, infrared or X-ray wavelengths. This is due to the physical process producing this radiation, which is thought to be synchrotron radiation. Three of the ORCs contain optical galaxies in their centers, suggesting that the galaxies might have formed these objects. Only in three cases twin intersecting rings have been seen and they are ORC J2103-6200, ORC J0356-4216 and RAD J131346.9+500320. The last one, RAD J131346.9+500320, discovered by the RAD@home citizen scientists using LOFAR data is currently the farthest and most powerful ORC discovered.

This article is issued from Wikipedia. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.