A circular polarisation survey for radio stars with the Australian SKA Pathfinder

TL;DR

This study conducted a circular polarisation survey of radio stars using ASKAP, detecting 33 known stars with significant circular polarisation, including 23 new radio detections, providing insights into their emission mechanisms and population statistics.

Contribution

First survey to systematically detect circular polarisation in radio stars with ASKAP, revealing new radio star detections and informing future survey strategies.

Findings

Detected 33 radio stars with >6% circular polarisation

Identified 23 new radio star detections

Provided flux densities and brightness temperatures for these sources

Abstract

We present results from a circular polarisation survey for radio stars in the Rapid ASKAP Continuum Survey (RACS). RACS is a survey of the entire sky south of $\delta=+41^\circ$ being conducted with the Australian Square Kilometre Array Pathfinder telescope (ASKAP) over a 288 MHz wide band centred on 887.5 MHz. The data we analyse includes Stokes I and V polarisation products to an RMS sensitivity of 250 $\mu$Jy PSF$^{-1}$. We searched RACS for sources with fractional circular polarisation above 6 per cent, and after excluding imaging artefacts, polarisation leakage, and known pulsars we identified radio emission coincident with 33 known stars. These range from M-dwarfs through to magnetic, chemically peculiar A- and B-type stars. Some of these are well known radio stars such as YZ CMi and CU Vir, but 23 have no previous radio detections. We report the flux density and derived brightness temperature of these detections and discuss the nature of the radio emission. We also discuss the implications of our results for the population statistics of radio stars in the context of future ASKAP and Square Kilometre Array surveys.