There is magnetic interaction between M-type star YZ-Ceti, and its exoplanet YZ-Ceti B

"An artist’s conceptual rendering of interactions between an exoplanet and its star. Plasma emitted from the star is deflected by the exoplanet’s magnetic field. That interaction perturbs the star’s magnetic field and generates auroras on the star and radio waves. Credit: Alice Kitterman/National Science Foundation". (ScitechDaily.com/Cracking the Magnetic Code: Distant Radio Signals Reveal Earth-Like Exoplanets’ Hidden Force)

The exoplanet can orbit very close to its star, especially if the star is a red dwarf. The interaction between a red dwarf and its planet can be interesting because the magnetic fields of a star and its planet can melt together. In that case, there is forming a plasma channel between the star and its planet. 

When a planet orbits its star that sends plasma with quite a low speed some parts of those particles can make the U-turn back to the star. And that thing can form auroras between the planet and its star. The exoplanet's magnetic field turns the direction of the plasma, and that thing forms the situation where it accelerates plasma but also the impacting ions cause radiation.

That plasma can also send radio waves that help to observe the planet and other participants of that solar system. The YZ Ceti is the first case when researchers have seen that kind of interaction. That interaction happens between star YZ Ceti and its planet YZ Ceti B. The magnetic bridge between that star and its exoplanet causes a situation, where the energy level of plasma is rising. And the particles impact each other. That thing can cause quite powerful radio waves. Or at least those radio waves are more powerful than they would be.