The European Research Council (ERC) has awarded two of its prestigious Starting Grants to ASTRON scientists for research projects using the LOFAR radio telescope. One project will use LOFAR to create detailed images of lightning on Earth, the other aims to detect space weather events and magnetic fields around exoplanets.
Published by the editorial team, 10 January 2022
Dr. Brian Hare will lead the project LIFT (Lightning corona Imaging From a radio Telescope), which will make use of the LOFAR radio telescope to create unprecedented images of lightning that are precise and detailed enough to allow for direct comparison with state-of-the-art lightning models.
Lightning has been a subject of scientific study since Benjamin Franklin but is still poorly understood. With climate change increasing the amount of lightning on Earth, and since many green energy sources such as wind turbines are susceptible to lightning damage, understanding this phenomenon is more important than ever before.
Experimental physicist Hare (ASTRON, the Netherlands Institute for Radio Astronomy and the Kapteyn Astronomical Institute at the University of Groningen) and his team use the LOFAR radio telescope to make 3D images of lightning (image 1). LOFAR does this in much more detail than other radio instruments can, explains Hare. Most lightning instrument have a resolution on a scale around 100 metres to maybe 10 metres in size, whereas lightning models work on a much smaller scale. This makes it extremely difficult to compare real measurements to these models. LOFAR however, can measure lightning on a scale of 10 down to 1 metre, which makes these measurements an order of magnitude more detailed. It also measures much faster: most radio instruments measure with microseconds between measurements, while LOFAR’s measurements are only nanoseconds apart. Hare: “LOFAR’s measurements actually come very close to the scale that models use. With the ERC Starting Grant we plan to push the resolution of LOFAR even further, so that we can finally compare actual lightning measurements to lightning models, enabling us to learn much more about the workings of lightning.”
LOFAR is currently being upgraded to LOFAR 2.0, giving it even better timing accuracy and a wider frequency band. Furthermore, Hare and his team will use the 2.1 million euros grant to develop beamforming techniques, enabling them to separate different radio waves that come from different places of the same lightning. They will also develop ways to measure the polarization of electric currents in the lightning flash, as to better understand how electric currents travel through lightning. The grant also allows Hare to hire two additional PhD’s and one postdoc for his team.
ASTRON staff astronomer and University of Groningen assistant professor Dr. Harish Vedantham has been awarded an ERC Starting Grant to detect space weather events and magnetic fields around exoplanets for the first time. Space weather is caused by a star ejecting huge masses of plasma and high-energy particles that can be detrimental to planetary atmospheres (image 2). Dr. Vedantham: “With this grant we will be able to detect telltale signatures of similar plasma ejections on stars other than the Sun. It will be an important factor in figuring out which stars are likely to have habitable planets.”
Earth has a defense mechanism against the space weather coming from the Sun: its magnetic field. But magnetic fields of exoplanets have not yet been measured directly. Dr. Vedantham: “We have several so-called scaling laws that predict the magnetic fields of exoplanets, but they have not been empirically tested with real data.” Dr. Vedantham’s project will use LOFAR data to measure magnetic field strengths of exoplanets to identify the correct scaling law. “This will be a big leap forward because knowing the exoplanets’ magnetic field is another crucial piece of assessing their habitability.”
Due to the faintness and rarity of the extrasolar signals, the project will have to tackle formidable technical challenges. Dr. Vedantham and his students, funded through the grant of 1.5 million euros, will search through 10 petabytes of LOFAR radio data. That is over a million compact disks or a thousand one-terabyte hard drives worth of data. The faint signals of interest must also be separated from human-generated interference in an automated fashion. “No one has attempted to look through so much data to find these faint signals so far. You really need a funding instrument with the ambition and scale of the ERC Starting Grant to make this happen. I am very excited to find myself at the start of this exciting path” said Dr. Vedantham.
Image 1:LOFAR measurements of lightning strike
The measuring of lightning through time. The left image shows a top-down view of LOFAR measurements of a lightning strike. Each dot represents a single measurement, whereas the difference in colors represent a difference in time. The dots shift from red to blue through time. The right image shows measurements of the same lightning strike, but from the front/side. By combining the left and right image a 3D image of a lightning strike can be created. Adding the data from the measurements in time, a 3D animation of the lightning strike can be created. (Credit: Brian Hare)
Animation about how LOFAR measures lightning strikes: https://www.youtube.com/watch?v=UcKQSG_3MUk
Image 2: Artist’s impression of space weather
This figure shows an artist’s impression of a solar flare hurling a large mass of hot plasma towards the Earth. The Earth’s magnetic field creates a protective cavity (shown in purple) and shields our life-sustaining atmosphere. The project STORMCHASER will study these processes in extrasolar systems. (Image credit: NASA)
More information about LOFAR: https://astron.nl/telescopes/lofar
More information about the ERC Starting Grants: https://erc.europa.eu/funding/starting-grants