LBA observations for project V653 semester 2024APRS

Roughly 1 in 10 O stars have been found to harbour extremely stable, ordered (usually dipolar) magnetic fields, which are of ~kG strength. The presence of such organized surface magnetic fields can channel and confine the outflowing stellar winds, creating a magnetosphere that can radiate in various wavebands. Several attempts were made to detect radio emissions from magnetic O-type stars at low frequencies. However, no detection was found, which can be explained by the absorption of non-thermal emission in sub-GHz frequencies due to the dense wind of such high mass-loss rate systems. The first exception to this scenario is the detection of sub-GHz radio emission with the upgraded Giant Metrewave Radio Telescope (uGMRT) from a binary O-star system HD 148937. The 325 MHz detection of this target makes it the lowest frequency detection of any magnetic massive star. The observed emission is non-thermal in nature, with radio luminosity much higher than expected. We attribute the possible emission mechanism to be either synchrotron emission from wind-wind collision, or Electron Cyclotron Maser Emission (ECME) from the magnetic primary. Given the extreme and unique nature of the radio emission from this system, we plan to follow up this target and make use of the high resolution of the LBA to pinpoint the emission region and the corresponding mechanism.