MeerKAT reveals a ghostly thermal radio ring towards the Galactic Centre

TL;DR

This paper reports the discovery of a thermal radio ring, Kyklos, near the Galactic Centre, likely a circumstellar shell around an evolved massive star, using MeerKAT radio observations.

Contribution

First detection of Kyklos, a thermal radio ring near the Galactic Centre, suggesting a new type of circumstellar shell around evolved massive stars.

Findings

Kyklos has an 80 arcsec diameter and a thermal spectrum.

It is likely a circumstellar shell around a Wolf-Rayet star.

The discovery expands understanding of radio structures near the Galactic Centre.

Abstract

We present the serendipitous discovery of a new radio-continuum ring-like object nicknamed Kyklos (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 arcsec and is located just 6 deg from the Galactic plane. However, Kyklos exhibits an atypical thermal radio-continuum spectrum ({\alpha} = -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.