MeerKAT reveals a ghostly thermal radio ring towards the Galactic Centre
Lundqvist, P.; Umana, G.; Filipović, M. D.; Camilo, F.; Loru, S.; Rowell, G.; Rizzo, J. R.; Riggi, S.; Trigilio, C.; Cavallaro, F.; Ingallinera, A.; Leto, P.; Bufano, F.; Norris, R. P.; Hopkins, A. M.; Bordiu, C.; Buemi, C.; Jarrett, T.; Cerrigone, L.; Dai, S.; Cotton, W. D.; Mackey, J.; Shabala, S.; Koribalski, B.; Velović, V.; Lazarević, S.; Payne, J.; Ruggeri, A. C.; Smeaton, Z. J.
Italy, Australia, United States, South Africa, Chile, Serbia, Sweden, Ireland, Spain
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 ∼80″ and is located just ∼6° from the Galactic plane. However, Kýklos exhibits an atypical thermal radio-continuum spectrum (α = ‑0.1 ± 0.3), 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.