Speaker
Description
In the solar system low frequency radio emission at frequencies ~200 MHz is produced by acceleration processes in the Sun and in planets’ magnetospheres. Such emission has been actively searched for in other stellar systems, as it would potentially enable the study of the interactions between stars and their exoplanets’ magnetospheres. Here we present a method meant to measure the flux density variability in an arbitrary number of directions from interferometric datasets. We implemented a multiplexed version of it to synthesize ∼ 200, 000 dynamic spectra of stars and exoplanetary systems from a ∼12,000 hours long, LoTSS dataset at ∼ 150 MHz. This additional diagnostic shows that 17 of the 134 (12.7%) targets previously identified in the LOFAR polarized images also show significant variability on few hours scale. The improved instantaneous sensitivity also lead to the detection of a rapidly drifting burst (Callingham et al. submitted) and 7 bursts from low-mass stars that vary on ∼ 0.5 − 1 hour scale, two of which hosting exoplanets. We argue that the strongly polarized structures in some of these dynamic spectra could originate from Electron Maser Cyclotron driven by star-planet interaction. I will give an update on the available software and future plans. Our results prefigure the larger populations of events that will be detectable by LOFAR 2.0 and the Square Kilometer Array (SKA), enabling detailed quantitative studies of stellar plasma environments and star-exoplanet interactions.
