American astronomers Sebastian Pineda and Jackie Feldsen have found evidence that YZ Ceti b – one of three planetary neighbors of the red dwarf star YZ Ceti (12 light-years away) – has a magnetic field. Indeed, observations with the Very Large Array radio telescope revealed a recurrent radio signal that was attributed to the interaction between the planet’s magnetic field and the parent star (natural astronomy3 April).
The planet’s magnetic field can prevent the planet’s atmosphere from “eroding away” under the influence of high-energy particles emitted from its star. If the rocky exoplanet YZ Ceti b does indeed have a strong magnetic field, this increases the chance that the atmosphere will bind to itself for a long time.
The radio waves generated by interactions between the magnetic field of an exoplanet and the star it orbits must be so strong that they can be detected from Earth. Therefore, Pineda and Viladsen chose planets very close to their star for their observations. This increases the chance of detecting their magnetic interactions.
Young star YZ Ceti and its planet, YZ Ceti b, are a perfect pair because the exoplanet is so close to its star that it completes a full orbit in just a couple of days. (For comparison, the innermost planet in our solar system, Mercury, has an orbital period of 88 days.) When a star ejects a cloud of charged particles (plasma), the star’s and planet’s magnetic fields interact, causing powerful radio waves to be generated.
By the way, this is not the first time that radio waves have been observed, which are attributed to the interaction between a red dwarf star and one of its planets. Three years ago, a team led by ASTRON’s Harish Vedantham made a similar discovery in the nearby red dwarf star GJ1151. (EE)
