Time-frequency spectrograms showing the simulated radio emission from star–planet magnetic interactions in the Tau Boo system for selected months; October 2010 (top), January 2011 (middle), and April 2011 (bottom). The y-axis denotes the radio frequency, while the x-axis represents time, with each tick corresponding to a single day within a given month (formatted as “day:month:year”). Frequencies are color–coded by the degree of circular polarization: blue indicates emission from the magnetic southern hemisphere, corresponding to field lines directed from the star to the planet, while red indicates emission from the magnetic northern hemisphere. In both cases, the color refers to the polarity of the field at the stellar surface (or carried by the wind).