Observing Flare Stars Below 100 MHz with the LWA

TL;DR

This study used the Long Wavelength Array to observe flare stars below 100 MHz, detecting a marginal flare from EQ Pegasi and analyzing polarization to identify genuine stellar flares.

Contribution

First low-frequency interferometric observations of flare stars below 100 MHz with polarization analysis to identify stellar flares.

Findings

Detected a marginal flare from EQ Pegasi with flux density 5.91 Jy in Stokes I.

Established polarization criteria for flare detection in low-frequency radio observations.

Measured brightness temperature of the flare as approximately 1.75 x 10^{16} K.

Abstract

We observed the flare stars AD Leonis, Wolf 424, EQ Pegasi, EV Lacertae, and UV Ceti for nearly 135 hours. These stars were observed between 63 and 83 MHz using the interferometry mode of the Long Wavelength Array. Given that emission from flare stars is typically circularly polarized, we used the condition that any significant detection present in Stokes I must also be present in Stokes V at the same time in order for us to consider it a possible flare. Following this, we made one marginal flare detection for the star EQ Pegasi. This flare had a flux density of 5.91 Jy in Stokes I and 5.13 Jy in Stokes V, corresponding to a brightness temperature $1.75 \times 10^{16}(r/r_*)^{-2}$ K.