Radio-emitting engines in M dwarfs

Radio observations are excellent probes of supra-thermal charges and magnetic fields in the coronae/magnetospheres of the coldest stars and brown dwarfs, and they are vital for identifying the impact of stellar plasma on exoplanet atmospheres and the coronal heating mechanism. Their strong magnetic field leads to radio emission via different mechanisms such as gyrosynchrotron emission, electron cyclotron maser instability, and plasma emission. As the ongoing LOFAR Two-metre Sky Survey (LoTSS) is the largest radio sky survey ever conducted (by source counts), I shall present the latest results on our effort to identify cyclotron maser emission from stellar and brown-dwarf candidates in the LoTSS data using optical and infrared catalogues from Gaia and Pan-STARRS. By using radio-detected population’s properties, we shall differentiate the two possible acceleration mechanisms: (a) chromospheric or coronal acceleration similar to that observed on the Sun, and (b) magnetospheric acceleration occurring far from the stellar surface similar to that observed on Jupiter.