Observations of radio pulses from CU Virginis

TL;DR

This study presents new radio observations of CU Virginis, revealing stable and intermittent pulse features, and discusses potential causes for observed period discrepancies, emphasizing the need for ongoing multi-wavelength monitoring.

Contribution

It provides detailed pulse profile observations at 13 and 20 cm and investigates the stability of emission peaks and timing discrepancies in CU Virginis.

Findings

Trailing peak is stable at both wavelengths.

Leading peak is intermittent at 13 cm.

Detected a discrepancy in rotation period measurements.

Abstract

The magnetic chemically peculiar star CU Virginis is a unique astrophysical laboratory for stellar magnetospheres and coherent emission processes. It is the only known main sequence star to emit a radio pulse every rotation period. Here we report on new observations of the CU Virginis pulse profile in the 13 and 20\,cm radio bands. The profile is known to be characterised by two peaks of 100$\%$ circularly polarised emission that are thought to arise in an electron-cyclotron maser mechanism. We find that the trailing peak is stable at both 13 and 20\,cm, whereas the leading peak is intermittent at 13\,cm. Our measured pulse arrival times confirm the discrepancy previously reported between the putative stellar rotation rates measured with optical data and with radio observations. We suggest that this period discrepancy might be caused by an unknown companion or by instabilities in the emission region. Regular long-term pulse timing and simultaneous multi-wavelength observations are essential to clarify the behaviour of this emerging class of transient radio source.