Evolutionary map of the universe: detection of the Wolf-Rayet star WR40

We present a radio-continuum detection of the well-known Wolf-Rayet star WR40 at 943.5 MHz using observations from the Evolutionary Map of the Universe (EMU) survey. We find that the shell surrounding WR40, known as RCW 58, has a flux density of 158.9±15.8 mJy and the star itself is 0.41±0.04 mJy. The shell size is found to be 9⁰× 6⁰, which matches well with the shell in Hα and is similarly matched to the shell at 22 µm in infrared. Using Gaia data, we derive a linear size of 7.32(±0.34) × 4.89(±0.23) pc at a distance of 2.79±0.13 kpc. We use the previous Australia Telescope Compact Array (ATCA) observations at 8.64, 4.80, and 2.4 GHz to determine a spectral index of WR40, which is estimated to be α = 0.80 ± 0.11, indicating that the emission from the star is thermal.