Astronomer Harish Vedantham of the Netherlands Institute for Radio Astronomy (ASTRON) and the University of Groningen has been awarded a ‘VIDI' grant of 800,000 Euros from the Netherlands Organization for Scientific Research (NWO). With this grant, Vedantham will use radio observations to answer a longstanding question: what determines the magnetic field strength of planets and their more massive cousins, brown dwarfs?

Published by the editorial team, 16 July 2021

In the e-MAPS (exploring Magnetism on the planetary scale) project Harish Vedantham will answer the question: what determines the magnetic field of an exoplanet? Answering this question is important because we know that a planets magnetic field plays a key role in determining whether it can harbour life. For example, the Earth's magnetic field protects our atmosphere from erosion by the Sun's constant plasma wind which is crucial for the Earth to sustain life.

Artist’s impression of Elegast, a brown dwarf. The blue loops depict the magnetic field lines. Charged particles moving along these lines emit radio waves that LOFAR detected. From a previous article by Harish Vedantham.  (Image credit: ASTRON / Danielle Futselaar)

This project will make intensive use of the Low Frequency Array (LOFAR). Thanks to LOFAR’s unprecedented sensitivity, it can detect radio waves that are created by the motion of charges in planets' magnetic fields. Observing these radio waves is likely to be the only viable technique to directly measure the magnetic field strengths of exoplanets. After using LOFAR to measure the magnetic field, follow-up radio and infrared observations to measure the objects' basic properties such as temperature, mass and rotation rate will be made. There are currently several theoretical models that make different assumptions to predict the magnetic field strength of exoplanets given their basic properties. These observations will lead to a critical test of these models and will determine which one is correct. Identifying the current dynamo laws will be a significant leap forward for exisiting and future efforts that use complex computer simulations to model the ability of exoplanets to host an atmosphere and life.

This project will search the entire northern sky for radio emission from brown dwarfs and exoplanets while piggy-backing on data from LoTSS – an ongoing survey of the northern sky with LOFAR. This strategy has already led to some early discoveries, led by Vedantham. He previously showed that brown dwarfs can be directly discovered using radio data from LOFAR alone which serves as a proof-of-concept for the VIDI project.

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