MeerKAT reveals a ghostly thermal radio ring towards the Galactic Centre

Abstract

We present the serendipitous discovery of a new radio-continuum ring-like object nicknamed Kýklos (J1802--3353), with MeerKAT UHF and L-band observations. The radio ring, which resembles the recently discovered odd radio circles (ORCs), has a diameter of sim 80 and is located just sim 6$^ from the Galactic plane. However, Kýklos exhibits an atypical thermal radio-continuum spectrum ($ which led us to explore different possible formation scenarios. We concluded that a circumstellar shell around an evolved massive star, possibly a Wolf-Rayet, is the most convincing explanation with the present data.