Chasing plasma storms on exoplanets

ongoing

Are there other worlds out there that can sustain life? A key factor in the ability of a planet to host life is its atmosphere. Stars can erode planetary atmospheres by bombarding the planet with plasma. How well planets can protect their atmospheres depends on the strength of their magnetic fields. We do not know the ultimate fate of exoplanet atmospheres because we have neither detected massive plasma ejections on stars nor measured the magnetic fields of exoplanets. Both of these shortcomings can be solved with sensitive radio observations at low frequencies (< 300 MHz). Previous radio observations did not simultaneously have the sensitivity and on-sky exposure to detect the faint, transient radio signals from stars and exoplanets. In this project, I will deploy a novel strategy to mine over 20,000 hours of existing data from the Low Frequency Array (LOFAR), the most sensitive telescope at low frequencies. I will achieve two orders of magnitude better sensitivity and/or time-on-sky than previous efforts to accomplish two goals: (1) the first detection of massive plasma ejection events on stars and (2) the first measurement of exoplanetary magnetic fields. My novel data-mining strategy, aided by my theoretical expertise in the generation and propagation of radio waves in astrophysical plasma, has already led to pioneering discoveries. These include the first evidence for radio emission from the magnetic interaction between a star and its exoplanet and the first discovery of a brown dwarf using radio data. An ERC grant will allow me to scale up my efforts to tackle petabytes of data and search for radio signals over trillions of image pixels to achieve the goals of this project. It will lead to a leap in our understanding of the plasma environment of exoplanets around stars of different types and ages and the underlying laws that determine the magnetic field strength of exoplanets.