Imaging exoplanets below the telescope stability limit

Abstract Exoplanet imaging is the main method for detailed characterization of planets orbiting beyond 1 au (ref. 1 ) but it requires suppressing the bright glare of the star to see the faint planet light. As well as sophisticated instrumentation 2,3 , effective image processing is necessary for starlight suppression, which continues to be a substantial limitation 4 . Standard algorithms use reference images for starlight modelling and thus they are limited by inevitable telescope instabilities that change from reference to science observation 5,6 . Addressing this challenge will increase the number of planets amenable to direct imaging and will be a notable step towards imaging exo-Earths with future observatories 7 . Here we present a new physics-based method for starlight subtraction. Our method combines a multistep optimization with a flexible physical model to produce a starlight model, allowing modelling and compensation of instrument instabilities. We use automatic differentiation (autodiff) 8 to optimize millions of model parameters. We demonstrate our method on observations from the James Webb Space Telescope (JWST) Near-InfraRed Camera (NIRCam) 9–11 coronagraph instrument. We achieve sensitivity 2–15 times superior to standard techniques, including the first detection of 51 Eridani b (ref. 12 ) at 4.3 μm. This is the first time, to our knowledge, that such an approach has demonstrated substantially improved sensitivity on real, on-sky coronagraphic imaging. Our framework can be extended to other current and future ground-based and space-based observatories, including the Nancy Grace Roman Space Telescope and the Habitable Worlds Observatory (HWO), potentially relaxing the unprecedented stability requirements needed to make these a success.