The Variable Radio Emission of V830 Tau and Its Putative Planet

Abstract We report on the first moderate-length timescale observations of a young stellar object at microwave frequencies. V830 Tau was monitored over the course of 8 days with the Karl G. Jansky Very Large Array at a frequency range of 4–8 GHz. Previous brief radio observations of this purported planet-hosting star indicated a radio-bright source with sparse evidence of dramatic intensity changes. Our observations confirm variability larger than a factor of 5 over the 8 days, with closer-spaced data indicating a long-lived flare event spanning multiple days. We discuss a hypothesis that the large, long-duration radio flare may be produced as a result of magnetospheric interaction between the star and its purported planet, using multiyear monitoring of a few active binary systems with the Green Bank Interferometer to augment our discussion. Although we cannot disentangle the effect of the large stellar surface area from any effects of orbital separation, the disputed star–planet system would have a large amount of power generated from the stretching and breaking of magnetic fields. If this long-duration flare behavior repeats with additional data on timescales close to the planetary orbital period, microwave signatures of interacting magnetospheres could be a new observational tool to confirm the existence of planets around young, magnetically active stars.